Hi Tink, ask what you want, the site is as much for you as it is for the regulars & their Sarcasm, your question as said is thoughtful, not many on here have come out with this before, That's 1 for you x, It is possible for a devise to reduce the speed as said, but just think of the hold ups! have you noticed the HGVs on the Motorways? prior to the 56mph HGVs travelled at 60mph, coaches used the third ( Outside lane) there was hardly any hold ups unless there was a bump, & that was mainly caused by a pillock in a private car. keep on posting, keep on looking, you will pick out the ones that are negative.