Yes, with tire wear off except when I was breaking it in.
I always change my oil first because it gains about 40hp and then break the car in online with tire wear and change the oil if it lets me every night.
If I remember correctly I started losing irrecoverable hp at 7500 to 8000 miles. I now have 22,000 miles on the car and have checked the rebuild weekly to see if it will add hp and despite the high price it won't help my hp.
Interesting! Can anyone confirm this? Does this mean if I race a few races with tire wear on that I will be able to do the rebuild and gain my hp back?
P.S. Thanks for all of your replies. It would be nice if an expensive engine rebuild would restore all the hp just like in real life. This is another one of those common sense fixes the game needs.