Apparently the ion engine used to power the next Mercury probe does 17.8 million mpg. I wonder if they make a marine version?

Maybe that's the next step in NASA developed techonogoly. We can only hope. What would happen to all that extra oil?

Make more plastic stuff we won't be able to do without.

Kidding aside, that is one phenominal engine!

&nbsp Pedro2,
ion drives produce very little thrust. The number quoted by NASA is equal to "10 US quarters". That's great for unmanned interstelar missions, but unsuitable for any environment with an atmosphere. These thrusters put-put along, accelerating a mass over a period of weeks or years. Yeah, after a few years you're moving along at a pretty good clip, near lightspeed, but that's not the sort of performance that soccer moms want in their station wagons.

&nbsp Another practical issue is the high power requirement of ion drives. It's okay for NASA to equip a spacecraft with a little nuclear powerplant. They do it routinely, but I wouldn't expect Toyota to start splitting atoms any time soon. The Japanese are, somewhat understandably, reluctant users of nuclear technology.

&nbsp The claim of X-number of MPG is probably misleading. From my understandine of ion drive, very little mass is accelerated to very high velocities to achieve thrust. They're probably talking about a miles per gallon of liquid xenon. Yep, you don't use much xenon, but the electricity required for ionization has to come from somewhere. You can have huge solar arrays for a mission close to the sun, or a little "Mr. Nuclear" nuke plant, neither of which are practical for the family car.

&nbsp By the way, Ion drives are not new. NASA built one back in the Mercury/Redstone days. We're talking almost fifty years. In the world of technology, a single decade is a long time. Several decades don't add up to "new".

&nbsp Anyway, ion drives aren't going to free the world from fossil fuels, but this is important technology. We need to use energy more wisely than we're using it today, and we need to look at all the available technologies. However, ion engines are suitable for spacecraft, not minivans.

&nbsp &nbsp Dan

&nbsp

Electric Golf Carts = unlimited miles per gallon ;-)
bicycles in Big citys suplimited by public rail transportation
are all practical ideas and practices, its really just an attitude that every person have their on personal fossil fuel burner.
The US is going to run out of oil rich countrys to accuse of having hidden weapons of mass destruction and be forced to revert to systems like the above.
IMHO