Car talk

Everybody knows that cars aren’t the most energy-efficient way to get around. But according to data collected by the U.S. Department of Energy, when energy efficiency is computed in BTUs (British Thermal Units, a measurement of the heat created by burning a fuel), cars aren’t as bad as light trucks and city buses that run on gasoline or diesel fuel.

When you move beyond energy efficiency to take a look at greenhouse-gas emissions, cars are still the big problem.

Better to walk or ride a bike.

Efficiency (BTUs of energy per passenger mile):
Light truck 7,004
Bus (city) 4,160
Airlines 3,587
Amtrak 2,935
Passenger car 3,549
Commuter rail 2,751
Bus (inter city) 932*

*This figure is for 2000, the last year for which this data was available. All other figures are for 2003.

Carbon-dioxide emissions (percentage of total emissions by source):
Automotive fuel 61 percent
Jet fuel 12.2 percent
Distillate fuel (diesels) 21.6 percent
Residual fuel (heavy fuel oil) 2.7 percent
Lubricants 0.3 percent
Aviation gas 0.1 percent

Source: Transportation Energy Data Book, U.S. Department of Energy