What’s new?This is Mercedes-Benz’s first bi-fuel passenger car available to the public (though not here in the UK). The standard 65-litre petrol tank is combined with an 18-litre natural gas tank mounted in the boot to provide a claimed 600-mile range. The standard E200’s supercharged engine is modified to run on either petrol or gas at the press of a button on the steering wheel.What’s it like?It’s a lot like a standard E200 with a smaller boot. Switching from petrol to natural gas doesn’t affect performance one bit. It’s no rocket-ship, but plant your foot and the response is crisp. Fuel consumption improves from 31.4mpg in petrol guise to an impressive 46.3mpg when you’re using gas. It’s just a pity the gas tank is so small. With only 180-odd miles between gas fill ups, you’re sure to be relying on the petrol tank a lot.Should I buy one?If you’re intent on lowering running costs but aren’t prepared to give up on luxury, then yes. It might not have the tyre-burning kudos of a E55 AMG, but the E200 NGT won’t leave nearly as big a dent in your bank account, and you’ll be doing your bit for the environment at the same time.