But they're increasingly coming under attack from environmentalists for guzzling too much fuel and spewing out too many emissions.
Diesel engines can greatly boost fuel economy, but they're dirty.
That's why DaimlerChrysler has partnered together with a company from Tulsa, Oklahoma called Syntroleum, to come up with a new type of fuel for diesels that burns much cleaner. The emissions that you get out of a vehicle depends as much on the fuel that you put in as the engine itself that's burning the fuel. You put clean fuel in, you get clean emissions out. DaimlerChrysler developed a concept vehicle called the Power Wagon that uses a big 7.2 liter diesel that puts out a staggering 780 foot pounds of torque. But the engine is nearly 20 times cleaner than a comparable diesel from the 1980's thanks to new diesel technology, but also because of the new fuel it runs on.