gas.jpgLast year, Dallas computer whiz Tony Scott drove a BMW M series, an expensive car that BMW advertises as "a race car for four." Then, contemplating the need for a new $1,200 set of Z-rated tires and a future of 15 miles a gallon on premium gas, he made a decision.

He traded the Beemer for a Toyota Prius sedan, a car that gets attention for its mpg, not its mph. One month later he bought another one for his wife, relegating their diesel Ford Excursion to what he calls "recreational status."

To be certain that he and his wife were comfortable, he made sure the new cars were tricked-out--- he bought them with all the upgrades, including leather upholstery and heated seats. Call it fashionable downsizing.

Today, after a year, his only complaint is about the Congress of the United States--- most of the tax credit for purchasing the hybrid cars was lost to the increasingly hated alternative minimum tax.

I've heard a lot of Prius stories since I wrote my first column about the car back in 2003. At the risk of sounding like a petro-zealot, here's another chapter in the saga.

While the more recent models are rated at 60 mpg city/50 mpg highway, our quaint 2003 model has only achieved 50 mpg a few times--- usually on smooth 50 to 60 mph drives, such as the trip from Santa Fe to Taos and back.

Last weekend, on the 640-mile run from Santa Fe to Dallas, it got only 41.1 miles per gallon--- but it was running at 70 to 75 miles an hour, breezing through the Texas panhandle on a day marked by dozens of tornadoes. I ignored the weather and listened to the audio edition of "Guns, Germs, and Steel" on CD ROM. The best way to reduce the gas mileage in a Prius is to drive it into a headwind on a rainy day.

During the last four years and 52,000 miles, however, the car has clocked in with nearly 45 mpg. A few tantalizing trips came close to 50 mpg. The gas tank is refilled with about 8 gallons of gas three times a month to cover something over 1,000 miles.

So it comes to about $67 a month for about 288 gallons a year, using regular gasoline that costs about $2.80 a gallon. Tony Scott is probably doing better, with total gasoline consumption well under 600 gallons a year for both cars.

How good is that?

Very. It's good for Tony Scott and for his family. It's good for the country.

According to survey data from the Energy Information Administration, gasoline consumption rises directly with income. The more income you have, the more gas you burn. Households with incomes under $15,000 a year burn only 647 gallons a year. Households with incomes over $75,000 a year burn an average 1,549 gallons a year--- more than twice as much (see table below).

Gasoline and Income

This table shows therelationship between household income and automobile travel
Family Income Number of Households Number of Vehicles Vehicle Miles Traveled Gasoline consumption
Under $15,000 10.5 million 1.4 13,400 637 gallons
$15,000 to $19,999 6.3 1.5 16,200 788
$20,000 to $24,999 5.6 1.6 16,600 794
$25,000 to $34,999 13.3 1.7 19,300 940
$35,000 to $49,999 18.9 2.0 23,800 1,183
$50,000 to $74,999 17.2 2.1 28,300 1,393
Over $75,000 20.6 2.5 31,900 1,549

Drive a fuel-efficient hybrid, however, and an affluent family can drive in style while consuming the same amount of fuel as a far less affluent family. I call that a move in the right direction.

On the web:

Table A2. U.S. Per Household Vehicle-Miles Traveled, Vehicle Fuel Consumption and Expenditures, 2001

April 30, 2006: Three Years of Prius

October 16, 2005: GPY, Not MPG

April 26, 2005: A Hummer of an Indicator

April 5, 2005: Time is Money

August 10, 2004: The Newest Investment Vehicle Has Four Wheels

May 13, 2004: The Prius Solutions: Take a Deep Breath

October 27, 2004: Liberty from Gas Pumps

March 27, 2004: The New Liberty Ships

March 14, 2004: My New (and Bigger) Prius

April 15, 2003: Defunding the Middle East