Best ways to keep a car clean!

I've just got given a not particularly dog-friendly company car (saloon and velour seats - eek!) and I have two Labradors! How can I keep the car in reasonable condition while allowing my Labs to enjoy their walks in all weather? I really do need fitted car seat covers and something to cover almost every interior surface as I'll end up getting in serious trouble if I have so much as a hair out of place when I hand this car back. Be great to be able to whip off the covers off quickly if I ever do need to use the car to transport a client, too!
Geoff Wilson, Woking