Crashable toy cars

Small boys, often with no prompting from television or anything else, usully acquire a violent and macabre sense of play. When I was young I didn't (as my contemporaries did) throw action men out of high windows and watch them float to earth while giving out clouds of black smoke from their flaming parachutes. I was more into crashing toy cars, which is quite satisfactory except that toy cars are far too strong to dent or crumple when crashing at the speeds at which a small boy can propel them.
So this idea is for a kit. The kit would contain a small chassis - essentially a metal plate with 4 wheels. It would also contain a negative and positive mould of the car's shape. To assemble, press ordinary kitchen foil into the negative mould and then press in the positive mould. Trim the edges, leaving foil tabs where indicated. Take the mould apart, and carefully put the foil car shape onto the chassis, slotting the tabs into the holes in the chassis. The foil car can then be painted or not, but will crumple and dent most satisfactorily when crashed into another, similar, car or a staitionary object.