Volkswagen has just delivered 250 of its dual fuel natural gas Golfs to Avis in Milan, Italy where they will join the rental car fleet. VW's dual fuel system allows the engine to run on either gasoline or compressed natural gas. Each fuel has its own delivery system and if one fuel runs out the system can automatically switch over on the fly. The vehicles will primarily be run on CNG in order to gain the air pollution reduction benefits of that fuel in the inner city of Milan. If the vehicles prove popular and reliable, VW and Avis may expand the program beyond the first 250 units.
[Source: GermanCarBlog, thanks to Christian for the tip]