Nice one. I'm happy i'm not the only one...
All races must be 100% clean laps for me. I'll restart it even if it's the last lap. I'll finish it only if i have no choice.
Always change oil and wash it after a race.
I usually have round numbers for power & weight.
I do everything possible with the suspension and weight distribution in order to get a good handling and fast times with a lower front or at least the same height on both ends. If needed, i raise the front, get my lap time, and tune it back.
Also keep tab C stock for stock, simulation races, like many of you.
When i'm done playing, i try to organize my garage and keep the cars in 'groups' (supercars, classics, race cars, rally cars, and so on). I don't spend more than a couple of minutes on this, i just try to keep them close for faster browsing.
I don't usually keep different versions of the same cars, with a few exceptions (GTRs, Evos, Imprezas...), but when i do, i get the most important models and/or the premium ones.
I can't accept a green Ferrari, a red R34, a yellow Aston Martin, and so on... it's just... weird or wrong for me. Some cars/brands have traditional colors so i usually respect that. A Type-R Honda must be Championship White. An Aston must have any tone of silver, black, or dark green. It's hard to explain. Also, most of my cars have darker wheels and red/yellow brakes. Maybe because i think they look more like track day cars that way. But i guess these last ones are more taste-related than OCDs...
Cheers!