Yeah but most older cars have steering wheels with no place for an airbag, and a slip-ring with 1 conductor for the horn. Maybe something from the 80s will have

Yeah but most older cars have steering wheels with no place for an airbag, and a slip-ring with 1 conductor for the horn. Maybe something from the 80s will have a 3 conductor slip ring for cruise control or something... that would be the hard part. Nobody who has an old car will want some ugly airbag tacked on somewhere. It has to be tightly integrated and be invisible or nobody would buy it.