Understandably racing is hard to train for as most muscles used in turning the wheel and such are
small and need proper twist to do it, so best way to train is to drive/race a car. When simracing then
a high forcefeedback strenght on a twitchy car can be quite a workout, bonus points for not breaking the wheel, and actually controlling the movements not just bashing the wheel around uses different muscles aswell so think about that.
If noone is looking you can take 2 dumbells and hold them in both hands like you were holding a wheel and then just do all kinds of movements you would expect to do while driving. Note that different core muscles work then seated and standing up
Picture contains a Matra from the early 70's, one can hear the v12 howling by just looking at the picture