Antimatter Car

What would be the fuel economy of a car powered by antimatter? --Myself

Note: I originally put this post on pastebin. 

Antilithium is probably the best type of antimatter for fueling a car. It's not a gas like antihydrogen or antihelium, but it's easier to make than heavier anti-elements. So first, I took the density of lithium. Theodore Gray's book The Elements tells me that lithium has a density of 0.535 grams per cubic centimeter. Obviously, antilithium will have the same density. A gallon contains 4000 cubic centimeters (~4 liters * 1000 cubic centimeters in a liter). So a gallon of antilithium would have a mass of 2140 grams. Wikipedia's article on antimatter weapons states that one gram of antimatter could be converted to 180 terajoules of energy. Thus, 2140 grams of antimatter could be converted to 385.2 petajoules of energy. Next, I needed to find the energy in a gallon of regular gas. A PDF from the University of Washington tells me that this number is 130,000,000 joules. 385,200,000,000,000,000/130,000,000 is 2,963,076,923, so antilithium fuel is about approximately 2.963 billion times as efficient as gasoline fuel. But how efficient is gasoline? Obviously, the fuel economy of cars varies hugely, but some blog says that the average fuel economy for new cars in 2013 was 24.9 miles per gallon, so we'll go with that. Multiply 24.9 by 2.963 billion and we get 73,780,615,382.7 miles per gallon.


How far could you get with such a car? Well, the average gas tank is about 16 gallons (so says Yahoo Answers, the very epitome of reliability), so a tank of antilithium would get you 1.18 trillion miles. A lightyear is about 6 trillion miles (thanks, Wikipedia) so a one lightyear trip would require five refills and a drive to Alpha Centauri (the nearest star, 4.2 light years away) would require over 20 refills of antilithium.


There aren't many antilithium stations in interstellar space^{[citation needed]}, but let's suppose there were. Would this drive be worth it? The cost of antihydrogen is $62.5 trillion per gram, according to this. There aren't any estimates (Really! None at all! And this is the Web!) for the cost of antihelium, so I have to blatantly guess. Let's just say that antihelium is ten times as expensive, at $625 trillion per gram. A website implies that antilithium is a million times harder to make, so let's assume it's a million times as expensive. That comes out to $625 quintillion per gram. Going back to the last paragraph, it seems that we'd need 684,800 grams of antilithium to make the trip, so the cost of fuel would be $428 septillion. Let's just say that this is more money than Bill Gates currently has.^{[dubious--discuss]} Oh and, someone would still have to build a highway, since car's don't work well in empty space.^{[citation needed]}