Fun facts, kinda OT, for the bored Options

[lapuwali]

1 US gallon of gasoline contains 104,000 BTUs of energy.
1hp = 2,540 BTU/hour of energy consumption.

A typical car requires about 9hp to cruise at 60mph, given aero loads and rolling resistance from tires.

So, if engines were 100% efficient at extracting energy from gasoline, you'd get 273 mpg at 60mph in a typical car. Since most cars actually get less than 30mpg, most engines are extracting roughly 10% of the energy in the gas and applying those to actually propelling the car. Most of the energy is being thrown out as waste heat directly out of the exhaust, or in heating up the coolant, the engine itself, the gearbox, and the tires.

btw, hydrogen has 180,000 BTU/US gal, so if a liquid H2 fuelled engine were produced that only had the same efficiency as a 27mpg gasoline engine, you'll see 45mpg typically.

Pure ethanol has only 70,000 BTU/US gal, for only 18mpg. E85 would bring this up to 20mpg. Britt noted E85 where he lived was $2.10/gal v. $2.58/gal for gasoline, meaning E85 costs 81% as much, but only takes you 74% as far...

Now, as for the efficiency of a Mr. Fusion powered car...

[scottb]

gaaaaahhhhh!!!

it gets into that conveying engergy thing..... heat... to friction .... to light..... to motion....all at the same time. little leeches sucking efficiency all throughout the process..... can't have 100% use of fuel to propulsion..... all reactions have an exothermic component and motion results in frictions of atmosphere and mechanics further reducing efficiency.......all working with/against each other.... convection/friction/evaporation/reduction...... all very complicated....

internal combustion is not all that efficient..... but awfully fun!