I'd like to switch to methane but I can't make up my mind. Despite the economic and ecological advantages of methane, I'd lose a lot of boot space in my car.

Many carmakers like Fiat, Opel, Mercedes-Benz and Volkswagen now mount methane cylinders in the underbodies of their cars. By December 2010 the Fiat Panda, Qubo, Doblò and Punto Natural Power, the Opel Zafira ecoM, the Mercedes Benz B180 Class and E200 NGT Class, the Volkswagen Passat and Touran Ecofuel were all available in Italy.
Generally speaking compromise conversions are no longer necessary when OEM models leave the factory already fitted for methane or methane-plus-petrol. However, care should be taken when converting cars to methane. Users are advised to have the conversion done by qualified technicians and decide with them which cylinders (size and capacity) take up least boot space without excessively reducing the amount of methane carried on board.