Avis Rent A Car is continuing its green expansion in Europe with the addition this month of VW Tourans that run on natural gas to its fleet in 15 German cities. And over in Portugal, Avis' uses 50 hybrids and has reduced CO2 emissions by 50 tons (I'm guessing this is compared to 2004 levels, since the hybrids were introduced in 2005, but I'm not certain). In Scandinavia, Avis is all about ethanol (and hybrids), with "over 400 ethanol-powered Saab 9-5 BioPower cars, 75 Ford Flexi-fuel and 20 Toyota Prius vehicles on its fleet." Avis UK offers carbon offset (using The CarbonNeutral Company) to online bookers.
I like Avis' earlier announcements about downsizing the family car. With clean(er) car rentals and things like car sharing, it's going to get easier and easier for people to have a car when necessary and not pay for it - and not pollute - when they don't. The decision is ours to make.