Carpets? I've been successful with a home carpet cleaner (I can't
remember the name, but basically a wet/dry vacuum, and a (hot) water
sprayer. Works quite well, overall. Sometimes I use spot cleaning.
I've also pulled carpets out and hosed them, scrubbed with a cleaning
machine (brush type) and rinsed. They need to be blocked (set so that
they dry in the shape they will be in the car) and dried, out of
direct sunlight if possible.

Seats: PVC... Any cleaner, probably is fine. Cloth/fabric... That same
carpet cleaner does them well. However, it does not get all the water
out so if you need to use the car, be prepared for a wet butt... <g>
Leather: Saddle soap. Or any commercial leather cleaner.