Hmmm . . . I would say the Sauber Mercedes.

 

It really is a tose up between the Minolta and the Sauber.

 

And i added Nitrous also....
Heres my setup

Engine
-70hp shot of N20
-Stage 4 Turbo

Suspension (F/R)
-Spring Rate 14.8/15.8
-Ride Height 55mm/55mm
-Shocks set at 8 bound and rebound F&R
-Camber 0.0/0.0
-Toe Angle 0/1
-Stabilizers 6/6

Gear Ratios
-1st 3.297
-2nd 2.391
-3rd 1.644
-4th 1.194
-5th 0.916
-6th 0.742
Final Drive - 3.100

TCS Controller set at 10 due to high speed (~280mph) wheelspin

Downforce 38/53

LSD
Initial Torque - 10
Accel - 40
Decel - 20

As far as driving the car just make sure you hold a steady 250ish mph through the turns, and when coming out of turn two hit the nitrous. With the 70 hp shot, you should have enough to hit 300mph....then run out

And as far as doing it with regular cars not race cars, ive gone 281.51 in a saleen s7

Edit: After posting, i attained a new top speed: 309.12mph

 

I guess lalo didnt care that much about the setup....

 

oh no, I did!! THANKS!!
Sorry, It's just that I haven't had a chance to play GT4 because I've been given a long term assignment teaching an advanced 7th grade science class