The letter (25 April) about feeling ill in the back (or the front) of any car can usually be solved by sitting the passenger on newspaper, preferably covered with plain paper. This might save your correspondent having to change his car. This tip was given us years ago while listening to a radio doctor answering questions on driving on holiday. Many head teachers also know the trick and use it for their pupils travelling by coach on outings. It does work for most people including those small enough to be in baby seats, even in Canada and the West Indies I am reliably informed. The family think that it works probably because it cuts the static charge - but I am no scientist, I just know that it works, even for dogs.