The Hypercar Fallacy: “1 plus 2 equals 10”

Lovins believed that combining two efficiency ideas would get us more than the sum of their savings, and called this his “1 plus 2 equals 10 equation.” Let’s check the math.

First efficiency idea: using carbon fiber: GM’s carbon-fiber Ultralite got 88 miles per gallon. That’s about four times better than normal cars were getting. For round numbers, say the “carbon” idea takes a normal car from 20 to 80 miles per gallon.

Second efficiency idea: hybrid motor: This is the idea Lovins combined with carbon to come up with the Hypercar. Using both ideas, he claimed that a “300-400-mpg four seater with widely available technology was possible.” For round numbers, say the hybrid idea takes a carbon car from 80 to 320 miles per gallon. That’s four times better than a carbon car, and 16 times better than a normal car.

So a four-times-better idea (carbon) combined with another four-times-better idea (hybrid) is 16 times better. So in this example, “4 + 4 = 16.” That’s what Lovins meant by “1 plus 2 equals 10.” The miles-per-gallon more than add up.

But the idea is to save gasoline, so we had better check gas savings.

Suppose the normal 20 mpg car used 800 gallons in a year. Then, assuming the carbon car would use only a quarter of this, or 200 gallons, it would save 600 gallons a year.

Similarly, assuming a hybrid motor added to a normal car would quadruple the miles per gallon, it would save 600 gallons a year.

But if a hybrid motor is added to a carbon fiber car what happens?

Intuition: Since a carbon car only uses 200 gallons, there is no way adding a hybrid motor can save 600 gallons.

Math: Adding a hybrid motor to a carbon car cuts gas usage four times, from 200 to 50 gallons, for an additional savings of 150 gallons, and a total savings of 600 + 150, or 750 gallons saved.

So a 600-gallon idea (carbon) combined with another 600-gallon idea (hybrid) makes a 750-gallons-saved idea. In this example, “600 + 600 = 750.”

The truth is that the hybrid-motor idea saves much less, not much more, when applied to a super-good car like GM’s Ultralite instead of to an ordinary car. This is well known, and it’s why GM never “thought of” adding a hybrid motor to a carbon fiber car.