in bought and done up cars not many will out handle or turn faster lap times than a bought and done up GTR. You have to know how to make them corner.
Many of the cars mentioned here are full bore LM or equivelant cars. Take the Calsonic, Unisia, or Penzoil GTR against many of the others and it is a much closer race.
In the Race Specced cars, thoughs that are GT500 or LM editions and few besides the very top of the charts can match the lap times. The CDMA Supra or equivelant is faster, so is the Cerbera, Toyota GT, R390 marginally, but with these high powered RWD cars you make a mistake and it is all over.
In my car club we used to have GT2 nights. Raced different cars in team events on a single TV per team. 90% of the time my team won using the Calsonic R34 GTR GT500 car. Why because while the other cars were capable of making that quicker lap time a spin here, off the road here cost you time in a longer event when you couldn't afford to do with close skill levels.
Personally I think the top two cars are the TVR Cerbera LM, and Toyota GT1 LM. They have the right balance for consistant lap times but can still punish you if you make a mistake.