I saw a MK1 Fiesta earlier this year - smoothed, lowered, carbon roof, wide wheels, I initially thought it was some scene "euro" car.
Second look I noticed buckets, Rev gauge mounted on the dash etc.
Got talking to the Owner, RWD V6 Cosworth - in a MK1 Fiesta, he said it's quicker in straight lines than Evo's/Subarus and will give most bikes a run for their money. He then left where we were opposite lock fishtailing up the road. The car had MAJOR work done to it though, firewall completely cut back and boxed to accommodate the Engine, transmission tunnel had to be hand made, Custom prop and much more with it really.
Non-Rover here but an Example of what can be done: Escort Cosworth in a Nova (and you know how small Nova's are!):