Given all of the concerns we have today over vehicle emissions, it's almost impossible to imagine that just a few decades ago, those short-sleeve and long-tie wearing engineers at General Motors came up with a car that would run on coal.

Yes, coal. Or, specifically superfine coal dust. The dust was blown into a turbine engine like you'd find in a jet and burned as fuel. Let us now dip our toes for a moment into the waters of nostalgia with a segment from an ancient episode of MotorWeek that features GM's weird experiment and all scratch our heads together.

Of course, GM was far from the first carmaker to experiment with turbine engine-powered cars. Chrysler famously produced a few dozen road-going examples that ran on gasoline, one of which has ended up in the collection of one Mr. Jay Leno. His is one of only two in private hands.

The turbine engine has a lot of desirable traits. It's relatively compact, at high speeds it's pretty efficient, and it can burn damn near anything as fuel, be that jet fuel or gasoline or Drakkar Noir. It's an incredibly smooth means of propulsion because the motion of the motor is all rotational, not reciprocating. It also sounds like a taxiing jet.

Unfortunately, the downside is that the exhaust produced by the turbine is hot enough to set just about anything on fire -- though Chrysler did figure out a way around this -- and it's not exceptionally efficient when it's idling at 22,000 revolutions per minute, as Mr. Leno points out in his excellent video on the turbine car. Add in the fact that turbine engines are inherently dirty and you see why the idea never really took off.

Leno eventually revisited the idea of the turbine-powered car with his one-off Ecojet project. This used a Lycoming helicopter turbine that was started on conventional Jet A fuel and then transitioned to biofuel which made for much cleaner emissions. His efforts weren't without their problems though, since he didn't go through the same kind of trouble and expense that Chrysler did to cool the exhaust.