Acceleration or top speed?
It really depends on the track and car combo.
For instance, if you took a GTR to London, and raced against an Elise, chances are you would lose. However, if you took a GTR to Monza and raced against an Elise, you would win.
In short, we need more info.
What would be the fastest road car to go round the nurburgring or tracks that are similar?
Here's the thread that nealcropper was referring too https://www.gtplanet.net/forum/showthread.php?p=1262439#post1262439
The nissan R390 road car will be the best for lap times.