Absolutely most efficient 40 mph transportation?
 

What's the best reguardless of cost, convience, speed? The only stipulation is it must be able to go at least 40mph, so no bicycles. The best I can see is bennelson's electric Kawisaki and the best production vehicle I've seen to date is http://www.myersmotors.com/ NMG!

Probably an aerodynamic gyro-train running a combined cycle powerplant: high-compression, turbocharged/turbocompounded diesel powering a steam turbine via waste heat. Vacuum sealed gyroscope on superfluid bearings...superconductors used throughout with ultra high efficiency motors/ultracapacitors for the traction drive system. :p

Gyro-Train
http://upload.wikimedia.org/wikipedi...nschienerp.jpg

If you meant personal transportation, I'd suspect a faired motorcycle (a la Craig Vetter) would be your best bet.

- LostCause

steel on steel
lowest cost per person
one ton of people 480 miles on one gallon

Well alrighty then.

I'd also guess a fully faired electrically driven motorcycle/trike.

My gyro train has too much frontal area.

A very efficient design would be a recumbent trike with a fairing and electric powered, solar charged would be very cool..cheap cost to operate and eco-freindly

biggest hurtles - light batteries.. the newest batteries would do this just fine however costs are very high.

Most efficient at what cost, and what range?

Why no bicycles? if I stepped my bike up to 72v it should be able to do 45mph.
My comuticar is supposed to do 40mph with a good new set of batteries and with a few upgrades should do 40+, current is 35-37mph with snow tires, needs an alignment and has old abused batteries.
My last Super Mileage Vehicle would do 45mph, got 245mpg, but wasn't road legel, I did build it for about $600 tho.

Bicycles are extremely draggy, especially at high speeds.

I don't know why I didn't think of this, but right now the most efficient 45mph transportation would be:

http://www.smh.com.au/ffximage/2007/..._470x312,0.jpg

If they didn't cost $400,000+, I'd buy one. :)

- LostCause