Hello, this here is a guide for Sunset Overdrive that will assist you in 100%ing the game.
In the guide, the achievements are ordered into sections.
Achievements in each section are ordered from Common to rare (from top to bottom).
If you find the following guide useful please considering upvoting it. :)

These are the achievements you'll get automatically as you play through the main story of the game, completing the quests marked on the map with a yellow marker. They're basically unmissable.

Oh the Horror!
Survive Horror Night
Unlocked after you beat the prologue mission titled "Horror Night"

Dusk 'til Dawn
Survive one night at your Fort
Unlocked after you beat the story mission titled "Amptastic"

Buck National
Become a reality TV star
Unlocked after you beat the story mission titled "Buck National vs The Apocalypse"

Plan B
Survive the glider crash and look for another way out of the city
Unlocked after you beat the story mission titled "Up in the Air"

That Balloon
You killed a balloon
Unlocked after you beat the story mission titled "It's Me! Fizzie!"

Scouts Honor
Become an honorary Troop Member by finding Bryllcream and defeating Norton
Unlocked after you beat the story mission titled "The Fall of Emperor Norton"

Ultra Mega Kill
That was a lot of pigeons
Unlocked after you beat the story mission titled "Tastes Like Chicken"

Save Everyone
Save Sunset City from Fizzco's second-most powerful robot
Unlocked after you beat the story mission titled "A Hero's Duty"

Excalibro
You forged the mythical Excalamune
Unlocked after you beat the story mission titled "Awesomesmithing"

This is my City Now
You beat the final Fizzco corporate machine
Unlocked after you beat the final story mission titled "This Ends Here" and finish the main game.

These achievements are awarded for completing the DLC quests; quests marked in pink and purple, and the side quests; quests marked in blue exclamation mark.
MOOIL DLC QUESTS : PINK MARKER
DAWN OF THE RISE OF THE FALLEN MACHINES : PURPLE MARKER
You will unlock side-quests procedurally as you complete main quests.

Find Bryllcream... again.
Find Bryllcream... again
Unlocked after you complete the first quest of the Mooil rig DLC marked in a pink marker on the map located in downtown.

Crude Oil
Arrive at the Mooil Rig
Unlocked after you complete the Mooil DLC quest "To the Rig!"

Ultimate Collection
Liberate all the comic books for the comic book collector
In little Tokyo, you'll find a mission titled "Find some comics", do this mission and you'll be presented with two more, asking you to do the same thing. Collect the comics three times. You will get this achievement upon completion of the third mission.

Big Tobacco
Smoking causes lung cancer, heart disease, and instant death
Unlocked after you complete the Mooil DLC quest "Mooil Meltdown"

It's Full of Stars
Light fires big enough to see from space
Unlocked after you complete the Mooil DLC quest "Pyro-techniques"

Seas the Day
Protect the boat from bombs, mortars, and OD
Unlocked after you complete the Mooil DLC quest "Protect the Ship"

Calamari
Defeat the DL-sea monster
At the final Mooil DLC quest, you will have to defeat a sea monster. Beating it and finishing the quest earns you this achievement.

Special Delivery
Ride a cargo container into the factory
Unlocked after you complete the first quest of the Dawn of the Rise of the Fallen Machines DLC. It will be marked by a purple marker on the map.

Saved
Find Fiona and Lou, then help them escape by fixing Snackwrap
Unlocked after completing the second quest of the Dawn of the Rise of the Fallen Machines DLC.

Defender of the Realm
Clear Fargarthia of a hidden evil
You get this achievement after completing a series of 3 side quests :

• Crimson Eyes in the North
  
• The Warlock's Red Gaze
  
• Wicked Watchers in the South

The first one will be available on the map after progressing through a main story, upon completion , the second one will be available, and then the third.

Equal Opportunity
Complete a quest from every Faction
As you play-through the main game, you will find working for many factions. You'll unlock new player forts where you'll be working for a particular faction for some quests before you shift to a new one. You have to beat at-least one quest from all the factions listed below :

• Oxfords
  
• Troop Bushido
  
• Fargarthians
  
• Las Catrinas

You will get this achievement as you play through the main game and/or complete side quests.

Roleplay While Rolepaying
Reach Level 99 in Ignatius' epic RPG campaign
Unlocked for beating the side quest titled "The Most Epic Quest for EXP"

Cosplay
Put on a robot costume and collect the kill codes
Unlocked after completing the third quest of the Dawn of the Rise of the Fallen Machines DLC.

Ballin'
Reroute the power inside the factory in the weirdest way possible
Unlocked after completing the fourth quest of the Dawn of the Rise of the Fallen Machines DLC.

The Most Punchable Face
Defeat Brandon. Like, for real
At the final mission of the Dawn of the Rise of the Fallen Machines DLC, you will have to defeat the Sunset TV host Brandon. Beat him and finish the quest to unlock this achievement.

A Boy's Best Friend is his Mother
Build the 'Feel the Burn' weapon for a guy who is stir-crazy... or just crazy
After you beat the first quest from the Mooil DLC ( the pink marked quest ) and get taken to the oil rig, you will see a quest on your map titled "Mommy Issues". Complete this quest to get this achievement.

The Pitch
Weapons design is a tough business
After you beat the second quest from the Dawn of the Rise of the Fallen Machines DLC, a side quest will unlock titled "It's just business". Complete this quest to get this achievement.

Not so Secret Ingredient
Get to the bottom of Fizzco's corporate secrets
You will need to beat a series of four side quests that unlock one by one as you progress through the main story. Keep an eye out for these quests as you keep completing the main quests. Beat all 4 to get the achievement. The quests are :

• Fizzco: The International Conspiracy
  
• Fizzco: The Secret Ingredient
  
• Fizzco: The Dirty Secret
  
• Fizzie: The Inside Story

Vat Pack Rat
Upgrade the Overcharge vats at every fort
You need to upgrade the vat at all 4 faction player forts by completing a side mission. The side missions are :

• Brewery Upgrade
  
• Theater Upgrade
  
• Boat Upgrade
  
• Hepcat Upgrade

Revolutionary
Take back Sunset City for the misfit survivors]
You will need to complete a series of side quests from Floyd that get unlocked late game.They are:

• Take Back the Streets: Old Factory District
  
• Take Back the Streets: Little Tokyo
  
• Take Back the Streets: The Harbor
  
• Take Back the Streets: Downtown

Big Break
Anybody can be a movie producer, because nobody knows what they do
In the Mooil Rig, as you beat the DLC quests, a side quest will unlock titled "Alan Smithee's Treasure Ocean". Complete this side quest to unlock this achievement.

A continuation of the previous part, containing achievements relating to DLC and Side quests.

Language Lessons
Work with Buck and Sam to create a new weapon
In the Rise of the Dawn of the Machines DLC, after you complete the DLC story quest "All you need is the kill codes", a side quest titled Cloudamajigger will appear. Complete this side quest to unlock the achievement,

Replay
Replay any Mission and complete it under par
Replay any mission and complete it under par time. I would recommend attempting a mission in which you have to go around the city and collect items. Replay such a mission and ignore every enemy. Just get where you need to go as fast as possible and complete the mission under par time to get the achievement.

These achievements are awarded for racking up specific kills, you should get some of them automatically while the rest need to be farmed if you don't get them in your play-through.

Grind Kills
Kill 100 enemies while grinding
Self explanatory, you'll get this automatically.
No farming needed

Bounce Kills
Kill 100 enemies while bouncing or while in the air
Self explanatory, you'll get this automatically.
No farming needed.

Let me Count the Ways
Burn, Shock, Freeze, or Enrage 1,000 enemies
Self explanatory. You'll get this automatically during your play-through.
Use the Flaming Compensator and kill ODs to get this faster.

Stylish Kills
Kill 500 enemies while at Style Level 3
The fastest way to generate Style Level is by killing Scabs with the Dirty Harry.
Unlock and upgrade all High style overdrives and the single shot style generation overdrive, keep grinding and bouncing around while shooting scabs with the Dirty Harry and you'll reach Style Level 3 very quickly, kills made during the style level being 3 must cumulatively add up to 500 to unlock this achievement. You should probably unlock this during your play-through automatically.

Grind Melee
Melee 50 enemies while grinding
You simply have to Melee 50 enemies while grinding. You don't have to necessarily kill them, meleeing and knocking them down counts too, though only once on a single enemy; you have to melee and knockdown or kill 50 separate enemies.

Orange Soda
5,000 OD Massacred
See Orange Soda II

Orange Soda II
15,000 OD massacred
You need to kill 15K ODs to get this achievement. This includes ODs only.
Scabs, FizzCo Bots or any other enemy besides ODs won't count.
The kill counter thats locates on the menu tracks all kinds of kills so don't follow that since you need to kill 15k ODs only, not including Scabs and Bots or anything else.
Beat the main game and do all the quests. After that if the achievement still hasn't popped, farm OD kills.
The easiest way to do this is by replaying Brewing missions and the campaign mission titled "Getting the Band Back Together". You get a lot of kills there.


Trap Kills
Kill 500 enemies with traps
You need to kill 500 enemies while defending your fort while it's brewing amps, exclusively with traps. A easy place to farm this is the "The Firework Show" quest in the Troop Bushido where you can use the Pop rocket trap to quickly dispatch a lot of zeds. Other traps that help in dispatching a lot of zeds fast are Dark Matter and the Pirhana Dispenser Machine.
You can also keep replaying the Midnight Brew challenge to farm trap kills if you prefer the old factory fort over Troop Bushido's fort.

Flung to Safety
Kill 100 enemies by flinging them into danger using the Springboard Trap
To get this, you need to get 100 kills by making the springboard trap fling ODs into another trap and then let the other trap kill the ODs.
The easiest way to do this is by placing a spring board trap and face it towards a Hack n' Slay trap. Let the spring board fling zeds to the Hack n' Slay trap and the Hack n' Slay trap will kill or atleast knock down ODs.
Kill 100 zeds in this way to get this achievement. You probably won't get this in one defense mission and will need to farm kills in this fashion by replaying a defense mission several times.

These achievements are related to Overdrives or Amps. Overdrives are passive boosts that you can obtain and upgrade via badges that are awarded to you by simply playing the game and doing stuff. Amps are active boosts that can be purchased or obtained from quests.

Badge
Earn a Badge
Unlocked after obtaining the first badge. This is story related and can't be missed.

Overdrive
Unlock an Overdrive
You can purchase overdrives using badges that you obtain as you keep playing the game. After you've obtained a few badges, go to the overdrive section from the menu and buy and equip a overdrive. The game will tell you how to do this so you can't miss out on it.

Amped Up
Equip 5 Amps on your character at the same time
Amps are active abilities you can equip from the character page.
There are two types of amps: Weapon amps and character amps. This achievement is awarded for equipping 5 character amps.

There are 5 character amp categories, namely: Melee amp, Hero amp, Hero amp 2, Epic amp and Dive bomb amp.
You can buy amps from Floyd. You will also obtain some amps from quests. Equip an amp in all 5 slots to get this achievement.

More Overdrive
Unlock at least one Rank 4 Overdrive
You can unlock overdrives using badges that you earn cumulatively as you keep playing the game. In the same way as you unlock a overdrive, you can upgrade them upto 3 times using the same badges that you used to unlock them in the first place. Simply unlock one overdrive and upgrade it 3 times using sufficient badges and you'll get this achievement.

Mixology 101
Collect 20 Amps from Floyd
You have to purchase any 20 amps from Floyd. To purchase amps you need either Overcharge or collectibles. The fastest way to get this is by completing quests and buying the collectible maps from Two-hat Jack. Once purchased, the location of all collectibles in an area will be marked on your map. Collect and use them to purchase amps from Floyd. You can find Floyd in a player fort. Any 20 amps count, including weapon amps.

These achievements are awarded for upgrading your guns to Level 5.

Favorite
Upgrade one of your guns to Level 5
See I like them all

Many Favorites
Upgrade 10 guns to Level 5
See I like them all.

I Like Them All
Upgrade 20 guns to Level 5
Weapons are upgraded as you keep using them. Kills made using a weapon earns it some xp, and eventually, upgrades it. Buy ample weapon and keep an eye at their effectiveness. Use the weapons against foes they're most effective against. For ex., use the flaming compensator exclusively against ODs, use the propane Launcher for mini bosses ( herkers; tank bots ), use the dirty harry for scabs and use Ak- F Off for FizzCo bots and so on. Once a weapon reaches level 5, de-equip it and use something else and level that up.
Focus on the rest of the achievements first. If you don't get it during the course of getting the rest of the achievements, farm kills with the weapon you want to level up with. See Orange Soda II achievement for farming purposes.

These achievements are related to collecting items or finding things around sunset city.

Who is Sending These?
Loot 25 emergency supply drops
Through out sunset city you'll randomly find TOOLKIT BOXES in your mini-map. You need to approach 25 of them and loot them. They appear at similar places. You can often find one in a tower in the Old factory base.
They're pretty common so just keep an eye on the map and loot the supply drop as soon as you spot it in the mini map.
You can also spot them by their distinctive green smoke. If you see a green smoke anywhere, go to it, it's a air drop.
These drops don't appear on the full map but only on the mini map.

Intel
Collect all 40 Smartphones
See It's Art Ok

Big Brother
Destroy all 150 Fizzco security cameras
See It's Art Ok

Shoe Closet
Collect all 150 shoes hanging from wires
See It's Art Ok

Litter
Collect all 150 scraps of toilet paper
See It's Art Ok

What's Your Sign?
Collect all 150 Overcharge hologram signs
See It's Art Ok

Hot Air
Collect all 150 Fizzie balloons
See It's Art Ok

Explorer
Find all 20 secret sightseeing locations in Sunset City
See It's Art Ok

Wire Tapping
Eavesdrop on nine conversations by hacking into satellites
See It's Art Ok

It's Art Ok
Deface 40 billboards with graffiti
All the above collectibles can be found in the in game map after you purchase their locations from Two hat jack. As you progress through the main story of the game and unlock different player forts in different parts of the city, you unlock collectible maps that you can purchase from Two-hat Jack. Keep completing the main quests and keep checking in on Two-hat Jack. With the maps purchased, simply open the map and collect the collectibles marked on your map one by one. You get the achievements once you collect all the collectibles.
SOME COLLECTABLE MAPS ARE ONLY PURCHASABLE AFTER BEATING ALL THE QUESTS AND COLLECTING ALL THE OTHER COLLECTABLES, SO DON'T GET WORRIED IF YOU CAN'T PURCHASE A COLLECTABLE MAP JUST YET. DO EVERYTHING ELSE AND THEN CHECK ON WITH TWO-HAT JACK
In case, for some reason, Two Hat Jack's Collectable inventory says sold out, even after you completed everything there is to complete in the game, here's a map that shows the location for all the collectables

The Collectable maps of the items located above ( besides smartphones ) are only purchasable after you've found one on your own. If you haven't, refer to the map and collect one item first before going to Two Hat Jack and buying a map for the rest.


Dawwwwww
Find all 12 of Ainsley's drawings scribbled on city walls
You need to travel to the following places and confront the 12 drawings.
The map bellow shows the locations for Ainsley's drawings. Go there and inspect the wall to find a drawing inscribed. Inspect all the 12 drawings to get the achievement.

These achievements are awarded by completing the many challenges located all over Sunset city. Challenges are unlocked by completing quests. You can keep doing challenges as you play the game if you want or you can complete every quest in the game first and then do all the challenges one by one.
For the sake of the game getting repetitive, I would recommend doing the challenges along with the rest of the game.

A Challenger Appears
Complete 10 challenges with at least a bronze rating
See The Champion

Second Place
Complete 30 challenges with at least a silver rating
See the Champion

The Champion
Complete 50 challenges with a gold rating
To get this achievement, you simply need to beat 50 challenges with a gold rating.
There is a total of 72 challenges in the game so you can leave out a good deal of challenges you feel difficult and only focus on getting a gold on those that you feel are easy.
I personally found the traversal challenges and Bomb delivery challenges easy. If you're good at traversal, you can try doing them. If you're good at shooting, you can do the shooting challenges.
Beat the main game and all the quests and attempt all the challenges, see which ones you feel are easy and try getting a gold in them.

Hardcore Buck National vs The Apocalypse
Beat the score of 400,000 on the Challenge 'Buck National vs The Apocalypse'
You need to beat the above said Challenge with 400,000 points to get this achievement.
The easiest way to do this is by completing the said kill objects that appear during the challenge ( bounce kills, grind kills etc ) as fast as possible. The objects earn you a lot of point and you can easily get to 400,000 in doing so.
Make sure you use level 5 rated weaponry to get kills as fast as possible. If you don't have level 5 rated gear, save this challenge for later when you get good equip.

Hardcore Buck Strikes Back
Beat the score of 500,000 on the Challenge 'Buck Strikes Back'
Same as Buck National vs The Apocalypse, use good equip and level 5 rated gear and do the objectives as fast as possible.

Hardcore Buck Stops Here
Beat the score of 600,000 on the Challenge 'Buck Stops Here'
You can very easily get this achievement by farming kills in the challenge.
Keep doing the objectives, and once you reach the "KILL ODs using catapult" objective, ODs keep spawning fast from a window in one corner of the map.
Once you reach this objective, go to that area and keep killing ODs as soon as they spawn from the window. Don't bother using the catapult and completing the objective or else the spawn point will change.
Use the propane launcher with the second amendmant amp to kill ODs fast while having a full stock of ammo.

I Should Get Paid for This
Beat Insomniac QA's high score of 534,080 on the Challenge 'Buck's Revenge'
This is a very difficult achievement where you score over 534,080 in the Buck's Revenge challenge, where it only takes 250,000 to get the gold medal. The real only advice here is to git gud.You will need practice and multiple attempts before you even get close to the said score. Bring your best rated gear to play. Flaming compensator, TNTTeddy, Propane launcher, HAIR SPRAY BOMB and anything that clears a crowd fast should be used. Don't get hung on killing ODs and focus on completing the objectives as fast as possible.
Use amps that maximise killing speed. The bouncing projectile epic amp can also come in handy for multi-kills.
Again, you will need several tries before you reach the score, so keep trying and you'll get this eventually.

Misc. achievements, ranked according to their rarity (top to bottom - common to rare).

Overachiever
You earned an achievement
Just earn any achievement to get this.

The .1%
Spend at least 25,000 Overcharge
Self explanatory. A fast way to obtain overcharge is to complete quests, especially the DLC quests.

Perfection
Complete an optional Night Defense without losing any of your overcharge
You will need to replay a optional night defense mission while keep all ODs at bay, preventing them from stealing even a single OD from your vat.
The easiest way to do this is to replay the optional night defense mission at the old factory ( the first base ). Use ample traps and place them properly, all around the base, but don't depend too much on them and you have to do most of the work. The Pop rocket trap is good for dispatching a lot of ODs fast. As for guns, the flaming compensator works wonders in dispatching zeds, but in case you run out of ammo for it, you can use the Propane launcher to take down hordes fast.
NOTE: You need to replay the mission. You will not get this during the first run. You'll only get this upon replaying a mission that you've already beaten, and, during the replay, keep your overcharge intact.

Appreciation
Watch the credits all the way through
Self explanatory.
DO NOT SKIP THE CREDIT SEQUENCE OR THE ACHIEVEMENT WON'T POP
In case you accidentally skipped it, replay the final mission again and sit through the entire credit sequence. The achievement will pop up after the entire credit has been shown.

The Floor is Lava
Chain together 100 traversal moves without stopping or touching the ground
You need to rack up a combo of 100 traversal moves to get this.
Easiest way to do this is by finding two bounceable objects, like two cars or two air vents located next to each other, and keep boucing from one to the other. Bouncing on the same object doesn't increase the multiplier but bouncing on separate objects keeps increasing it by 1 per bounce. Keep bouncing on two objects next to each other and land when it reaches 100. The achievement will pop when you land and the 100x combo will register.
DO NOT KILL OD AND INCREASE MULTIPLIER AS IT WON'T COUNT

Can't Commit
Equip one piece of clothing from each Faction at the same time
As you progress through the main story of the game, you will encounter 4 factions. Beat all the missions of the factions and you'll receive a piece of clothing that you can equip by going to the cloth vendor. The pieces of clothing that you need to wear are :

• Oxfords faction - Tops:- Outerwear:- Oxford Backpack
  
• Troop Bushido faction - Tops:- Tops:- Troop Shirt
  
• Fargarthian faction - Bottoms:- Bottoms:- Fargarthian Armored Pants
  
• Las Catrinas faction - Head:- Body Art:- Muertos

Complete the main quests and you'll unlock these clothing eventually. With all of them unlocked, equip them and you'll get the achievement.

Going to Need a Bigger Closet
Collect 250 fashion items
You need 250 fashion items in total to get this achievement. Every fashion item is included, including the ones you already the start the game with, the ones you get from quests and the ones you can buy from Calista for free ( for 0$ ).
Just beat the game, completing all the quests and you'll get a lot of clothing from the quests themselves. Then come back to Calista and buy out everything, starting from things that are cheap. Don't waste money on a 1000k dollar suit, buy cheap things.

Not the Boss of Me
Replay the final mission and defeat the boss under par
Self explanatory. Just replay the final mission and the beat the boss fast; under par time. You get the achievement once you finish the quest under par time.

Worst Job in the Kingdom
Replay the Floating Garbage mission and beat the score of 50,000
Self explanatory.

Fizzie Says April Fools
Ha, ha! I can't believe you fell for that! (Acquire Worst Job in the Kingdom)
Unlocked automatically with the above achievement after replaying the floating garbage mission and beating the score of 50,000.

Crash Landing
Destroy 25 Fizzco Blimps just because you can
You need to shoot and blow up 25 flying FizzCo blips to get this achievement. You can find blips floating around all over the city, but if you need to farm it you can do so by going to the location of "GLIDER CHALLENGE #2". If you've beaten the main game, a blip should spawn there every time. Keep gong there and shooting down the blip until you get the achievement.

Out of Stock
Destroy 250 Overcharge XT vending machines
You can find these all over the city, especially in the malls in Little Tokyo.


FTR, this is how one looks like.
Keep traveling through malls and destroy every time you see one of these.
This is not in a collectible format and you don't need to break 250 separate ones.
You can break the same vending machine 250 times if you want. After breaking one, you can quit and load up the game again and the machine will be back up.
If you travel to the location for the challenge 'Episode 2 - Buck Strikes Back' there will be a multi-story car park nearby with around 20 or so of these Vending machines. After travelling to the area, proceed to smash all of these Vending machines, then go back to the challenge and load it up. Once the challenge loads up, immediately quit it and once the game loads up again, all of the Vending machines will be intact allowing you to smash them again. Keep repeating this process until the achievement unlocks.

Big thanks to Scotty & Aceman417 and xhunterrrr from XboxAchievements.
Please check out their guide [www.xboxachievements.com]
If you found the guide useful please considering leaving a like.
If you spotted any mistake or typo in the guide and/or need additional help regarding 100%ing the game, or have literally any query regarding the guide, please comment it down below and I will get back to you asap.