Depends on which car, exactly. Not all Car A and Car B are made the same.
But more favorably, I would go with Car A. similar to the GTR-35 TC, that car tears up a lap time in 5:52s, because it has brute power and magically shifts it weight in the right way most of the time.
The other day, I took out the FORD Lightning, Engine Limited down at 505pp, it weighed around 1800kg, I came in 4th of 12. It was hilarious, at how that heavy truck handled it so well, and if I had a plow on the front, I'd have cleared all the snow and cars together. The opponents were all regular tuned cars. I need to tune it better, and win with it.