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...

[lapuwali]

Cost is an interesting issue, actually. There are 42 US gallons in one barrel of oil, and the recent peak price has been $66/barrel, so each gallon of oil costs $1.57. Now, each barrel of oil actually only produces 19.5 gallons of gas (plus 4 gallons of fuel oil, plus kerosene, yada, yada). Let's say 60% of the money produced by a barrel of oil comes from gasoline, so $40 per "barrel" of gasoline, or $2.05 per gallon of refined gasoline, just in the price of the raw materials. Throw in transport and refining costs, and taxes, and it's a wonder gas prices in the US are still only $2.60/gallon (more or less, depending on where you are). 8M barrels of oil are produced per day, or 156M gallons, or $320M worth of oil, sold for $406M, for 22% gross margins (before transport and refining costs, as well as lining the pockets of the oil execs). EVERY DAY.

But, I also like internal combustion, and would vastly prefer it to, say, an all-electric. I'd much rather have a hydrogen powered V12 than an equally powerful electric, simply because the V12 sounds so much nicer. Gasoline-electric hybrids are unsatisfying as they generally add a lot of weight to the car, and aren't as efficient as a "proper" gasoline-electric hybrid would be (i.e. a 30-40hp tiny gas engine only there to charge batteries, with electric motors doing all the driving). If you're going to go for efficient, might as well go all the way.

For the powerheads, since typical efficiencies for IC engines are 10-20%, there's a LOT of power available in the fuel that's being lost. Turbos exploit some of the heat lost to the exhaust stream, but a full gas turbine with some regeneration (again capturing lost exhaust heat) can approach 60% efficiency. Same amount of fuel, but 3x the power. Or same amount of power, and 3x the mileage. Problem with gas turbines is they make terrible direct drive engines (major lag, very inefficient at light loads), so they're better suited for being the fossil fuel side of a hybrid.