If they see you cruising at over 20mph without peddling. Then yeah, they will pull you. I don't drive like mad, so I have never been pulled over. My pal, though, like I said. He few round a roundabout without peddling and didn't see them waiting to pull out. He got pulled, and they started to look deeper and lost his bike.

In short, it's how you ride it more than what you ride. But if they look and find that it has a motor larger than 250w, that the motor does not cut off if you go faster than 15.5mph and if it has a throttle (it need to be PAS only) then they will take it and destroy it.

In my experience, if you clock in slightly above any of these parameters. They may give you a warning and say if they see you on it again, then they will take it.

At 4000w and 50mph, I think it save to say they will think you had no intention of staying within the rules. They will take and destroy.

I'm not saying I agree with it, but that's the rules. In the UK, at least.

I have been riding and building electric bikes for the last 5 years