Right-click on CMS 2018 in Library, select Properties and....

1. Disable Steam Cloud saves;

2. Verify integrity of game files ;

3. Download the free Tuning DLC.

The first two steps should avoid any potential problems in loading the game; the third is needed to access the Tuning Shop and find parts such as Headlight B etc

Please note further that the guide is based on playing in Normal mode. If you decide to start in Expert, then most of the visual aids are unavailable.

There's no real need to bother with it. Many of the skills demonstrated here do not carry forward into the game proper, they have to be earned again and not until after investing a good deal of time, effort and patience.
There is no manual nor a need for one, in my opinion. The game is self-intuitive, easing you in and enabling natural progress - i.e. straightforward jobs to begin with, gradually increasing in complexity and finally introducing the skills and tools needed to restore and rebuild barn/scrapyard finds should you wish to do so. My advice - without wishing to sound presumptuous - is: Don't run before you can walk, be patient and persevere and just let the game develop

Notes on Control Basics to get started :

WSAD = movement
LMB = Action (with hints shown at the bottom of the screen)
RMB = Radial menu with options including Examine mode, Move car etc

Investigate all workshop items, especially on expansion. Some are purely ornamental, others are practical. Those you can interact with will highlight yellow to indicate they can be used.
The lack of a workshop map or similar encourages the player to use logical thought process. For example: there are three parts to a front shock absorber assembly: what do you need to dismantle and re-build....?
It only takes a few minutes to wander around, clicking on this and that, an exercise that will prove especially useful when you're stood there, scratching your behind, and wondering where that bloody engine has got to. Just like I was. For ages...







Note: There are, however, no calendars with bosoms. Believe me, I've looked everywhere....

Orders are received by telephone at first, and can also be accessed by tablet once upgraded. There are four types - Normal; Money or Experience bonus; and Story(campaign). Each affects the speed of your progress and in which areas, it's up to you to decide your priorities.
It is essential that you familiarise yourself with ALL aspects of the order - and not just the faulty parts list - to ensure successful completion.

To view an Order: face the car, right-click for Radial Menu, choose option Car Status:



Early-level orders will often list the faults for you, in which case click on the asterisk next to the part and it will highlight blue on the vehicle (more below)
Others will require manual diagnosis. When tackling these, I'd suggest - where possible - using Examine mode and the real naked eye (in dismantle mode) before doing anything else. Most problems can be identified by these methods until you reach the levels where diagnostic tools become available as upgrades.

Although it's not my intention to give specific answers to the problems encountered, just a few clues to the often frustrating "....sound in engine bay" and how to diagnose without special tools and without too much engine stripping (hopefully....). These represent only what I've found, listed in the order in which I personally look:

Common:
Air filter, base, cover - Examine mode
Ignition distributor cap, rotor arm - Examine mode
Rocker arm - Examine, naked eye (rust)
Valve push rod - naked eye (excessive black colouration)
camshaft cap - Examine, naked eye (rust)
Timing components - Examine, naked eye (rust) (mostly, although some need taking off the engine)

Less common:
Alternator - naked eye (rust) or take off
spark plug (s) - take out
clutch components/flywheel - test track and/or dismantle gearbox (easy enough)
Crankshaft, bearing cap, piston, rings, rod cap - hopefully, you won't have to go there before Level 9 where a certain specialist upgrade will diagnose before you strip the engine....






Tip: To complete an Order, don't forget that you need to replace the faulty part(s) in the exact same position, which is straightforward with, say, an oil filter, not so with a bushing, spark plug, ignition coil or any other multiple part. You can't swap and change, it must be bad for good, straight swap.
So, to pinpoint the part's correct position, click on the star/asterisk next to it on the Faulty Parts Found list and it will highlight blue and remain so until you re-click the star. You can highlight multiple parts, too, which makes a complex job a whole lot easier.
I'll leave readers to find out what happens to the highlight with the engine out, however........

As you progress, orders will become more complicated with a multitude of jobs to perform. How you tackle them is up to you but remember that one of the most common frustrations is forgetting to replace a relatively obscure part and having to start the job all over again. My own preference now is to break multi-job orders into sections, fixing each in turn.

For example, and not necessarily in order:
engine bay;
gearbox;
front and rear brakes;
suspension;
body- and interior- work.

This obviously necessitates breaking off and visiting the shops more often but it's a lot less likely to result in frustration-induced mental instability...

A checklist for when you encounter: "There are no items to work with"

1. Are you using the correct replacement part? Some engines - for instance V8 OHV and variants - require their own specialised version of otherwise commonly used standard parts. It's very easy to purchase an incorrect replacement when you're fixing similar engines one after the other. As a general rule of thumb, it is often a single letter that will catch the unwary (my own bete-noir is the valve push rod, even after 300+ hours...);

2. Have you followed the correct procedure to prepare the replacement part for mounting? Multi-part assemblies - front shocks, rims & tyres - require pre-assembly and/or preparation. Without this, they will be "no items to work with" The necessary tools are in the workshop;

3. Have you downloaded the free Tuning DLC? Some cars require custom body parts, such as headlights. They are recognised by a letter designation after the part - Headlight A, for example. These can only be found in the custom bodyshop.

4. Mods - if you wish to use modded cars, there is a separate store for these parts, too

Shopping. A pain when the missus insists you accompany her, an even bigger pain in this game because you can't slope off to the pub.
The shops can be accessed via the desktop pc, or the tablet once upgraded.
For simple one-job orders - or by following a workflow such as described above - you can rely on memory most of the time. For complex engine repairs, however, the parts list can be a 'mare to begin with, especially when working on V8 OHV and variants.
When I first started, I'd use pencil and paper and a self-produced spreadsheet printout with a generic list of parts in the order of my preferred workflow, and empty boxes alongside to either tick or make notes.
But then, after 400+ hours in-game, would you believe I finally discovered a little tab in the extreme upper right-hand corner of the online shop that says Shopping List. "Wots all that about then?" I asked myself, because I have no friends and nobody ever listens to me anyway. And then it was simply a matter of trial-and-error to discover the simplest of procedures...

1. dismantle as necessary;
(1a. repair salvageable parts at workbench (when you begin restoring, for example);
2. go to Inventory, change sort-filter to "By name" (for ease of reference), right-click items needing replacement;
3. go to online shop, left-click the afore-mentioned and fill yer boots (or your shopping trolley)....
4. clear shopping list by calling up the radial menu and selecting the option.

But remember: never, ever, give the missus your credit card and say 'Buy yourself a little present, dear, while I nip for a pint...'

Nowadays I concentrate mainly on restoration, but I still use an abridged version of the spreadsheet to keep a note of specific expensive-from-new parts to look out for when visiting barns and the junkyard. Hence the Repair? column in the worksheet which highlights whether or not a particular part can be repaired at the workbench (see The Junkyards and Barns, below). So it's reproduced here if it can be of any use to anybody:



As a reminder: make sure you have the Tuning DLC. It's free and without it you won't be able to fix certain cars/models

By following Step 2, you will have discovered how to access Upgrades which are purchased with experience points that can take some time to earn and should therefore be used wisely.
Look at the upgrades available and prioritise according to how you want to play the game. There are those that will increase productivity and those that help efficiency at the cost of speed. Nevertheless, when starting out, there are two or three that will save you a lot of guesswork, needless engine dismantling and playing upsy-daisy with the car-lifter, and I would personally prioritise these.

Barns become available at Level 6, and new locations (maps) can be awarded on completion of Customer Orders, found in crates (again on job completion, or discovered in barns), or by searching the Junkyard which is accessible at Level 13.

Both locations provide spare parts of varying condition, as well as cars for restoration, but bear in mind that the skills and workshop upgrades necessary for optimum performance of each are not available until the following levels:
Level 25 - 95% chance of successful repair;
Level 30 - 3-lifter garage expansion, spray shop, tuning bay and welding equipment needed at......;
Level 35 - the ability to repair body parts.

Note that Barns/Sheds disappear once visited. You can, of course, buy and store cars/parts until you reach the above levels but you can only store 12 cars per level of parking, and extra space is expensive.

Notes on Repairs:
Be aware that no part below 15% condition can be repaired (except batteries which can be re-charged).
Also, some parts that can be fixed on a particular make/model of car, might be irreparable on another (I'm not mentioning them darn pesky vpr's again....)
Interiors cannot be restored (unfortunately) but can be enhanced by using the interior repair kit found near the office.
Some body parts that cannot be repaired on stock cars, can be on mods

Once you begin renovating in earnest....

DLCs: many will only spawn either as Orders, Salon and/or Auction. Should you wish to renovate a Pagani (for example) then all you need to do is manually amend the config file. Right click on the game and follow:
Manage>BrowseLocal Files>cms2018_data>StreamingAssets>Cars, then add Shed,Junkyard to the spawn command
I've done this for several desirable models without breaking the game.

Cars from scrapyards will require extensive restoration. I tend to have several "on the ramp" and, as mentioned above, keep track of parts I need by using the shopping spreadsheet for reference when visiting the scrapyard and barns. It would be easier to just buy them but I'm a tight old knacker.....

So that's it. Neither definitive nor concise and undoubtedly incomplete, so I'll add to it as and when I think of something else. In the meantime please feel free to comment, whether good, bad, or completely irrelevant, I've got wide shoulders and a thick skin and all feedback is appreciated.

Now I could be a complete anorak and sign off with "Happy Spannering, Mechs!".....

(....but I won't....)