Two-thirds of all the BMWs sold in Europe are diesels.  They're powerful, reliable and much more fuel efficient than their gasoline counterparts.  With emissions regulations tightening on this side of the Atlantic, BMW has plans to start selling a lot of diesel-driven Bimmers here in North America.

So what makes these diesel engines so great?  Well, like Mercedes-Benz, the BMW engines are quiet and extremely powerful - which they should be considering the price of their cars - but they also use the latest technology to reduce emissions resulting in a "clean diesel" engine.

Basically, each car has a 25-litre tank full of a special high-tech additive: pee.  Yeah, that's right, each car has a tank of piss sloshing around in it.  This "additive" is sprayed into an emissions chamber which somehow reduces the amount of greenhouse gasses that come out of the exhaust.

I don't understand how the heck it works either, but if this car company is able to make a massive change in the greenhouse gas output of its entire vehicle fleet hopefully it's the first sign of more big changes on the way from auto manufacturers.

» MSN Autos