I got this game a few days ago and it's been tons of fun. I looked through this thread today and after seeing the two BMW M4 Replicas, I decided to do one myself, since I DO love the M4. It didn't come out anywhere as near as well as I wanted to. The back, especially, came out poorly due to a lack of good taillight shapes to work with and the body's shape. I picked this shell because it was the closest I could do, though still far enough away. The front came out OKAY though. As for the engine, I tried to make it as much based off the real thing as I could, and then I ended up just matching the RPM, Compression, HP, and Torque output of the real S55 engine, though I researched and made sure to use an AlSi block and Forged Crank. I matched the 0-60 time as close as i could and put the top speed under 200 (I know that it's limited to 155 in USA, but probably can't pull 200 unlocked). It's light and I was too lazy to keep tuning to increase the fuel economy. I was mostly going for the design.
Also big thanks to Tom, who's videos gave me ideas on creative use of vents.
Maybe when i get bored ill post my original designs. Might do more replicas. Any ideas what to do?