-> I think everything in both red & white RE-GReddy 6 resembling the Yamaha prototype are purely coincedental. According RE-Amemiya's site; the car is powered by a highly modified (as usual) 13B kai 20B engine:
Clicky on link:
^ Sure it may have some design cues from the OX99-11 and the legendary McLaren F1, but this car is (I think) purely original.