Auto Bild recently conducted a comparison between two fuel-efficient SUVs the Lexus RX400h hybrid and the Mercedes ML 320 CDI diesel. On a coast-to-coast run, the Merc bested the Lexus in overally fuel economy, but it's important to bear in mind that most of the miles driven were on the freeway, where a hybrid's regenerative brakes have precious few opportunities to recharge the batteries. The RX also beat the ML in city driving, where hybrids excel by design, and features significantly lower emissions, but there's also the battery-disposal question to deal with. We're calling this one a wash for now. For greenies, which one you'll choose depends on the kind of driving you do most.
Diesel Bests Hybrid in Cross-Country Fuel Consumption Test [Green Car Congress]