Does anyone know the Cd of an XJS vs XJR ?
I ask because today I was confronted with some empty track and a sunny dry road.
My XJR was still pulling like a train at 195km/h (121mph) up a gentle curving incline when my self-preservation instinct kicked in.
I know the XJR was not speed-limited and apparently could do 163 mph when new, and the XJS was supposedly a 150-155 mph car (albeit with 3 auto gears).
it got me wondering what the respective drag coefficients are...

 

I believe the CD of the XJR was 0.37 and the XJS was 0.40, better than the E-type believe it or not.
I also believe that the top speed of the XJR was in fact electronically limited, as where many of its competitors of the day (BMW, Mercedes etc).
The top speed as quoted in the sales brochure was 155mph (250kph) and the XJS had a top speed of approx. 153-155mph depending on model.
In the days of the XJR whilst it and many similar models/makes were perhaps capable of higher speeds, I believe the manufacturers seemed to have an informal agreement to limit top speed to approx. 155mph. This is evidenced with Jaguar by the fact that all XJR's from 1994 until 2008 all had a quoted top speed of 155mph despite increased power/torque outputs over that time.

John Herbert
(1996 XJR)

 

Thanks John.
0.37 is not too bad.
I think the Vauxhall/Opel coupe in the 90s was about 0.25
Apparently a Mk II Ford Escort is about .40 and the snout nosed RS is about .35

i watched the Netflix movie about Shelby. When they turned the Cobra into the Daytona Coupe it gained about 15 mph testing on the straight at (I think) Sebring, and used 30% less fuel

 

I can assure everyone that the maximum vehicle speed of an XJR is NOT electronically limited. If it had been, it would have been my job to calibrate this function in software.

BTW, I very much doubt a 90s Vauxhall / Opel coupe, achieved a CD of 0.25. That is very low.

Force required to overcome aerodynamic drag is proportional to the coefficient of drag and the frontal area

The power required to propel a vehicle is proportional to the cube of the speed.