Why my wife and I didn’t buy a Toyota Prius

In April this year my wife and I were involved in a four-car pileup . Neither of us was hurt, but our car, a 1993 Honda Civic hatchback, was written off as a total loss by our insurance company. We had to get a new car.

Because we live in an inner city neighborhood and park on the street, we wanted a small car. We also wanted an economical car, one that would cost little to own and run over a lifetime at least as long as our old Civic’s 18 years.

The cost of 18 years’ of gasoline is significant. For some cars, it’s comparable to the initial cost of buying the car. Would getting a hybrid car end up saving money?

Consumer Reports provides estimates for the overall mileage of cars derived from a representative mix of highway and city driving. For the Honda Fit (the car at the top of our shopping list), CR‘s overall mileage is 33 mpg. For the Toyota Prius (the world’s most popular hybrid), it’s 44 mpg.

My 10-mile commute breaks down into 4 miles of city driving and 6 miles of highway. My wife gets to work on the Washington, DC, Metro. In a typical year, we drive about 6250 miles. Maintaining that rate over 18 years yields a lifetime total of 112 500 miles. Driving that distance with CR‘s overall mileage rates, a Fit would consume 3409 gallons; a Prius, 2557 gallons.

The Prius is considerably more expensive than the Fit. CR gives the range of their MRSP as $23 520 – $39 525 for the Prius and $15 175 – $19 540 for the Fit. Given our driving habits, would a Prius prove cheaper than a Fit in the long, 18-year run?

Not knowing the future price of gasoline, I framed the question as follows: At what gasoline price, averaged over 18 years, would the Prius become cheaper? The answer is $9.79. We bought the Fit shown here.

Going electric

Why not get an electric car? The Nissan Leaf is a four-door hatchback like the Prius and the Fit. At $35 200 – $37 250, its MSRP is as high as that of a fully tricked-out Prius. Even with its high fuel economy (CR gives the Leaf’s overall “gas” mileage as 106 mpg), the Fit would still prove cheaper to run. What’s more, the Leaf’s modest 100-mile range is too short for comfort.

At last week’s Industrial Physics Forum in Nashville, Tennessee, I learned that the limit on an electric car’s range is due not so much to the capacity of lithium-ion batteries but to their density. You can’t arbitrarily increase an electric car’s range by adding more batteries without weighing it down.

Even if the ranges of electric cars did match those of gasoline-power cars, electric cars are more expensive. What’s more, given that 70% of the electricity in the US is generated by burning fossil fuels, electric cars aren’t necessarily greener than gasoline-powered cars. The greenness argument appears valid, but it misses a key point: efficiency.

In the case of electric and gasoline-powered cars, the sequence of energy-conversion steps starts with a fossil fuel and ends in a moving vehicle. Both cases entail burning a fossil fuel to drive a mechanical device, either a power station’s turbine or a car’s internal combustion engine. The additional steps are different for the two types of car.

For an electric car, you need to convert kinetic energy into electricity, transmit the electricity to an outlet, charge the battery, and power the engine. For a gas-powered car, you need to refine the crude oil and transport the gasoline to a gas station.

I haven’t been able to find figures about the efficiencies of all those steps, but everything I’ve read about oil refining says it consumes a lot of energy. Indeed, according to a 2004 study by the California Energy Commission, oil refineries are the biggest consumers of energy in California.

So my hunch is that even if you live in a state, such as Kentucky, that gets most of its electric power from coal-fired stations, running an electric car is still likely to be the greener option. And if scientists and engineers succeed in building a better battery, I expect my next car will be electric.