We all know you can crash in a car with 90bhp, but I'd bet quite a lot of money that the *generalised* trend is that, in a 17-20 year old's hands, the lower the powered car, the less serious single vehicle accidents are.
I dunno but low powered small car, often quite old, for a new drivers means if an accident does happen the consequences, especially for passengers, is likely to be more serious than if they were driving something newer and better specced.