A stiff yet mildly soft bristle brush, a bucket, liquid Tide and a shop vac.
Make a detergent solution in the bucket, you want lots of suds.
Use the brush to apply suds only to the fabric and clean away.
Do not soak the seats, using the suds only will help.
Vacuum mostly dry with shop vac and let air dry. Voila!
Other methods require patience and skill.
Recovering requires a heavy duty sewing machine.
Lots of nice Vinyl fabric or other at Michaels for about 13.99 a yard.
Use the old cover as template and be creative.
Pull the new one on over a large garbage bag, it helps it slide
on nicely, then pull out the plastic bag.
You may have to replace some foam if it's worn out
when you have the old cover off.
Secure with hog rings in original location.
You could always just have an upholsterer recover them,
but for that price just buy a new set of seats.
Starting around $300 a pair plus mounting labor and hardware.
Again, you have to be creative.

