about to rewire classic car, mosfets?

Hey people, I am about to rewiere the switch panel in my classic mini and was wondering if anyone had experimented with using MOSFETs instead of relays. The swithces will be: rear heated screen, hazzard lights, lights and starter button The obvious advantages are: Smaller form factor No switch noise Theoretically unlimited lifespan So whats the disadvantages? Thanks Ian

The main concern is that using them takes more careful consideration of the MOSFET's specifications for the application, designing for protection against transients when connected to inductive loads, and general fear of electronic things. Relays are pretty much immune to mishandling, while MOSFETs require more care to safeguard against damage from electrostatic discharge. Lots of people just prefer simple stuff like relays over mysterious electronic stuff that have no moving parts. Relays are easier to work with when dealing with bidirectional signals since they don't care which way the current is flowing as much as transistors do. Double throw is easier to do with relays also. With proper heatsinking, MOSFETs that can handle a lot of current are available. If the circuit is put together with it just hanging in the air, it'll overheat.