This is prob a noob question but will s4 seats fit in my 1995 audi 90cs

 

Anything will fit in any car - just depends on the work you want to put in. You can make them fit I'm sure, but it won't be a bolt-in install and will require custom rails/brackets, and if they're powered (most are) you'll need to create the wiring and interface it into the car. If they're heated, you'll need seat heater controls and wiring harnesses (or custom jobs again) to put them to use. So yeah, they'll fit just fine, as long as you're willing to put in some painstaking work and time.