Saving Money: Gallons Per Mile

There was an interesting article in Science Daily about changing the way we describe fuel economy to help people make better decisions. It’s not about how many miles per gallon a car gets that’s important, but how much total gas it uses.

When I was shopping for a car, I did a comparison between a hybrid vehicle and a normal gasoline vehicle to see if the total amount of money I would save would offset paying more for a hybrid. My conclusion was that I didn’t save money by buying a hybrid because I drive so few miles and the normal gasoline vehicle I use was already fuel efficient. I drive at most 60 miles every two weeks on the freeway, so in a year I drive about 1560 miles a year. Now the two vehicles I will be comparing are the Honda Accord (30-mpg highway) and the Toyota Prius (45-mpg).

Miles Per Gallon Gallons Per Year
15 104
20 78
25 62.4
30 52
35 44.6
40 39.0
45 34.7
50 31.2

The amount of gasoline I save goes down as my car becomes more fuel efficient. The most money is saved by going from a car with really bad fuel economy to a car with slightly better fuel economy. Going from 15-mpg to 20-mpg saves about the same amount of fuel as going from 25 mpg to 45 mpg. The Prius saves 17.3 gallons of gas each year over the Accord.

Price Per Gallon Cost Difference Per Year
4 69.33
6 140.00
8 138.67
10 173.33
12 208.00

If I look at for the pricing of an Accord LX-P Automatic Sedan for $21,348 versus a Prius Base 4dr Sedan with Package #2 for $24,11, the price difference is $2,762. Of course the price varies depending on the specific car you choose and when you actually go to the dealer. It’s easier to talk down the Accord price since people are flocking to hybrids because of the rise in fuel costs. Hypothetically if gas was $12 a gallon, I would have to drive the Prius for 13.3 years to break even on the cost differential if I don’t account for the interest in the bank I could gain on the $2,762. The warranty on the battery is about 8 to 10 years, so I would most likely have to replace the battery too in that time at additional costs. The tax credit for hybrid vehicles would help, but it is no longer offered on the Prius. This makes the Accord the better choice over the Prius if I was just considering costs. That’s with gas costing $12 a gallon. I drive a ridiculously low amount of miles since I commute to work on my bicycle, even in the rain. I know it will still be this way for about 4 more years. After the amount of miles I will have to drive may go up, since I drove 7500 miles and spent $1k on gas a few summers ago. That however was an isolated incident, which makes me never want to commute to work ever again.

Your mileage may vary. You should do your own math to see if it makes sense for you to purchase a hybrid. Always do the math, never assume anything.


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