They are all the same. I've got a Camry and an Impala and there is no detectable difference. It's all about your settings. Max downforce front and back, gear ratio set to 390kph, camber 2.5 front and 1.7 rear with toe out front at -30 and rear at 0. I passed the last car just before the long straight.
Put racing softs on a purchased Jeff Gordon Impala, no other changes. I hand to activate a ton of assists however just to keep the damn thing on the road. Was a real workout with the DFGT.