I've never wrote much guides before, so don't expect too much quality here, but I'll be sharing what I know after 200 hours of this game. I hope this guide helps with getting your store up and running, and hopefully automated enough so you can focus more on collecting your own collection and focus less on managing your store (ironically).

May 2nd - Guide written.
May 6th - Typo fixes and additional early game information.
May 7th - Profit optimization updated.
May 13th - Added a few more information and tips thanks to findings from user corocoro.

You start with only Basic boxes and a triple level single sided shelf. Focus on just the Basic Supercar Box x20/x40 sales as they'll be your main source of income, but also focus hard on Box Packs once they're unlocked, as technically they're counted as a different type of product and customers can and will buy both. Also start to unlock new series as soon as you can, as the higher the tier, the better they sell.

Rent: You can actually skip paying rent until the deadline, it's cheaper than paying it everyday. Don't actually forget to pay rent on the last day of the deadline though, or you'll be blasted with a mandatory payment + penalty invoice fee for late payment.

Opening boxes and getting fast cars: Don't be shy to open a decent amount of boxes a day (I recommend x8 a day for early game). Eventually you will know when you have enough income to start opening an entire carton of 8 x 8 big boxes without affecting your profits. If you get Mythical+ cars, trying to withhold your urge and don't sell immediately, keep it and race with customers for more high rarity, expensive cars.

Selling Single Cars: When you have a somewhat substantial collection, you can start aiming for one (and only one) cheapest display shelf at $400 to sell cars you don't want. The most cost effective display shelf is the Big Car Display Shelf, so once you have will eventually want to start getting around 4 of them, adding more if they are cleared out before the end of the day.

Race Track Table: Get one as soon as possible to get yourself some passive income, and also allows you to start racing opponents for bonus income. Once you have enough room, you eventually want a maximum of 6 tables as any more than that is a waste of money since opponents won't sit on more tables.

TIP: Did you know you can attach your wall display shelves outside the store? It might help with cosmetics, but the main benefit is that it gives you extra wall space. There is no robbery/theft mechanics in this game anyway if you're concerned with security.

Sales and Shelves: Of course you want a variety of products you can sell, though you only really need to sell the 2 most expensive singular and boxes you can buy to optimize profits, as customers will by a rather total set amount of boxes regardless of type.

Pricing: Always sell +10% higher than market price for all non-single car products, and don't forget to update it every 3rd day. You may want to consider rounding down (not up) if you hate typing too many digits when handling as the cashier, at least until you can afford hiring workers.

If you want to optimize your sale profits, sell only 2 or 3 of the most expensive supercar series you can buy and not all of them. The reason is because having more shelves doesn't actually increases sale quantity, but instead dilutes your profits instead of concentrating them into more expensive products. You will see that having one shelf for every series will have customers barely clearing out one line of a type of product if they're lucky at the end of the day, instead of almost clearing out two whole single shelves.

By the end of the early game you should have 4 Red Double Sided Shelves. What you should sell in your store for maximum profit is as follows:
1 - Most expensive Supercar Box
2 - most expensive Supercar Box Pack
3 - 2nd most expensive Supercar Box Pack
4 - 3rd most expensive Supercar Box Pack/Most expensive track box//Most expensive car shell


Pro Tip: Setting up your stock having different item types per self like the screenshot above actually increases your sale more than if it's an entire cabinet with one type of product. The AI seems to act funny when many available products are on sale, and will be "encouraged" to buy Box Packs as if they're like small boxes, just like the old Demo.

The other furniture you should get would be exactly 6 Race Track Tables. You do not need more than 6 tables, as the AI is very bad at recognizing empty spaces and will just immediately proceed to shop instead when a table is occupied and the 5 other tables are empty. Add more tables once there's a new patch to fix customer table AI.

Start getting cashiers and hire employees to manage checkouts. Get your first one as soon as you can afford both at the same time, it will save a lot of your trouble and you can use that time to race customers for extra profits. Once you have cashiers you don't need to round up any numbers anymore, just 10% markup for products and 15% markup for single cars.

Get around 3-4 Big Car Display Shelves to sell cars that should not be bundled, see Single Cars section to determine what to sell or bundle.

A lot of these information are courtesy of user corocoro's findings:

By late game, it's best to minimize or even eliminate sales of displayed cars. Display cars are placed in the same product category as Wheels, Replacement Car Shells and Car Launchers.

As which item of the category customers pick seems to be determined by relative shelf space to other products in the same product category, the cars will push everything else to kingdom come.

TL;DR: In end game, don't bother selling individual cars unless they're more valuable than Replacement Car Shell Set Pro (over $25 profit), they should all be bundled. Replacement Car Shell Set Pro (~$25). It also means you shouldn't stock Launchers or Wheels (verification in process).

So, pick the most profitable of each, calculated by profit per unit * units/shelf space. End game means you shouldn't sell cars below $40 because the missed sales opportunity means you earn less.

What about just displaying the cars without selling them? Simply DO NOT. The coding seems to be the same as a customer being dissatisfied with a product that is "too expensive", your sales will be immediately deleted in half if you do that.

Selling - Individual cars be safely sold at 15% markup without customers complaining about the car being too expensive, and unlike regular products the market price doesn't change. Once you get a Bundle Table, you have to know what cars should and shouldn't be sold on the shelves and should be bundled instead if you want to maximize profits, I call this the profit minimum. If a car's market price is lower than the profit minimum, you shouldn't sell it alone on shelves and instead just bundle all of them unless you're really desperate for cash. To maximize profits, cars above these certain prices should be sold on displays, and bundled if below:

• Common $2.22
  
• Uncommon $4.46
  
• Rare $7.43
  
• Epic $17.82
  
• Legendary $222.75
  
• Mythical $1188.00
  
• Special $1930.00

Summary:

• Basic - Bundle all except Chronos Yellow.
  
• Faster - Bundle all Legendary, Mythical and Special. Display all Epics except Horus Black and Blue. Bundle all Rares except Penelope Black and Brown. Bundle all Uncommons except Pheme. Display all Commons except Helenes, Mimas, Ocipetes.
  
• Pro - Bundle all Specials and Mythicals. Bundle all Legendaries except Enifs and Oberon Red. Display all Epics, Rares, Uncommons and Commons.
  
• Elite - Bundle all except Asteria Gray, Asteria Green, and Ironclad Yellow.
  
• Champion - Display all.
  
• Extra - Display all.
  
• Souvenir - Display all. Souvenirs can never be bundled, display them regardless of price if you intend to sell.

Skill Cards are super important, especially when racing an opponent with the same rarity as you. A lot of the Skill Pack Series 1 cards are mediocre, so just focus on Skill Pack Series 2 instead.

Below is just my personal thoughts and my rankings. You are free to disagree with this list.
Tier List

• Swap - The hardest skill card to use, but the most broken skill in the game if you know when to time it. The most optimal way to use Swap is when your own car just completed 1 lap while your opponent is about to finish a lap. Time the Swap right and you can gain 2 laps in a very short amount of time while your opponent has to start the lap all over again. The only difference between the Swap rarities is how long it takes for the swap to occur, Level 3 Swap is instant while Level 1 Swap has a delay.
  
• Time Rewind - 2nd strongest skill in the game, unlike all the other offensive cards below this, the effect is instantaneous with zero delay regardless of rarity, only duration is different. Technically Level 1 Rock is stronger than Level 1 Time Rewind, but Level 3 Time Rewind is busted and if the AI plays bad cards/timing, this card alone can win games just like Swap.
  
• Ghost - Best defensive card. Grants immunity and a small boost in speed. Better version of Shield. Pop it before your car gets hit by any offensive cards below this, like Rock, Ice, Wind, Missile, Bomb.
  
• Teleport - Good defensive card. It's harder to use than ghost and shield. Lower levels have a delay, which sometimes will fail and this will be wasted if you don't react in time, so take care of timing. This card breaks in the Shark Table if the car lands on the start line, making a lap count as 2 instead.
  
• Rock - Best obstacle card. Spawns a rock behind you. The amount of stall it causes is the longest, even Level 1 is very strong, and especially good Level 3. Try popping it immediately at the start of the game to gain ground against the AI and give yourself a long headstart. Sometimes Rock can win games alone too like Swap and Time Rewind. In the Shark table, you should place the rock directly on the place where the shark chomps, to maximize delay.
  
• Ice - Second best obstacle card. Spawns a field of ice behind you. Weaker than Rock as it slows down your opponent substantially instead of a complete stop. Place Ice also on the same location as the Rock on shark table.
  
• Missile - Best offensive card. Summons a missile from the start line and chases the opponent. Missile's disruption is stronger than Wind. Different levels of Missile fly at different speeds.
  
• Bomb - Spawns a bomb behind you. Weak obstacle card, with barely any delay in time caused. However, can still be useful in the shark table if you place the obstacle where the shark is.
  
• Wind - Second best offensive card. Summons a tornado in front of you and chases the opponent. This card is not useful if you're a little ahead of your opponent, though Level 3 Tornado is very potent. Wind and Missile have both trouble catching the fastest cars so they're worse than static obstacles.
  
• Shield - Shield is easier to use than Teleport, but is directly an inferior version of Ghost. It also does not help you at all if you're behind. It's still not a bad card though, but not amazing.
  
• Boost - Below average, the amount of distance you can earn is minuscule. Best used immediately at the start of the game if you want to use it, before your opponent stops you with their offensive cards. Boost is largely depend on how fast your own car is. On high end cars it gives you another lap. On low end cars it's too pathetic to use. Laugh and be relieved if you see the AI uses Boost especially when your car is a tier higher.

Get your first racetrack table as soon as possible, winning customer cars means good income, especially for Legendary and higher rarity cars.

Fun Fact: The description says hourly income, but in reality it only counts per finished race, so it can go over several hours if both AI has slow cars.

Rule of thumb: Your car automatically win opponents 2 rarities below you without any skill card activations. You can still bring skill cards as insurance, and not using them means they're available on next game, but there's no need to use them with this rule of thumb. E.g. Special beats Legendary and below automatically, Legendary beats Rare and below automatically, etc.

Opponents with the same rarity or a rarity below can win against your car depending on their skill choices, therefore use your own skill cards where needed to win.

Play how you want, the general meta to maximize gains and minimize losses is to have your 2 most expensive cars (Crius and Zelus preferably) + cheap normals and uncommons from Champion series.

Personally I play as a rare car donor with the new Steampunk and Extra series so others can also complete their collection anyways, whenever I have spares I just donate to other people, though bonus if you can communicate your trade with your partner.

Not much I can add, but if you see Legendary+ cars, obviously you should invest some money on it. The vending machine is more of a late game investment when you already got the store running fine and then you can waste some money after business hours.

Another late game location where you can get some Extra series cars. There's two playstyles you can go for in the very short amount of time it's open.
1) Pinpoint hunting, only look for light blue borders for extra cars
2) Brute force, mass left click + E and buy everything on sight without pause while searching. This should be done when searching inside boxes.