Gustav from M5Board.com has driven the G-Power BMW M5 Hurricane RR V10 bi-kompressor producing up to 800hp. His experience was captured in a video and several pictures. Gustav’s personal comment about the car was the following:
And hit 296 km/h on the GPS. Considering the traffic and that it was 3 o’clock in the afternoon a weekday I was happy with that. That is well below 300 km/h (186 mph) on the speedometer, probably 200+ mph on the speedometer on a stock M5. Only had it in MDM and S5 mode. Grip was surpisingly good, I beleive alot attributed to the very hot weather with 33,5 degrees celsius which made the tires real sticky. However there where instances where it was traction problems on onramps etc upto 160-170km/h. S5 really felt (and sounded) like S6 or at least alot more than the S5 of a stock M5. Clearly more than 500hp acting on the rear axle.