SIR – The speed limit in this country is 70mph, so why are cars designed to go faster?

Why can’t I design a device that could be fixed to signs, be it 30, 40, 50, 60 or 70mph, a device which automatically switches off the engine if the vehicle exceeds the limit?

Someone may complain that this could be dangerous to other road users. But no, if the vehicle isn’t breaking the speed limit to begin with, then there will be no problems.

It would also stop the ton-up merchants on our motorways. We have visible speed cameras on urban roads, but none on motorways.

And why haven’t I designed a device that could be embedded into the tarmac and melt the snow/ice? There would be no need for the gritters that come out at the wrong times.

Football pitches have under-soil heating, why can’t we have under-road heating?

We have digital devices, we can put men into space but we can’t solve the weather (snow and floods) and we still have problems opening a tin of corned beef.

B Barraclough, New Works Road, Low Moor