Blame the economy.  Blame the cost of gas.  U.S. drivers logged fewer miles last year.

Last year, U.S. drivers logged 35.7 billion fewer miles over 2010 — down 1.2 percent — to 2.963 trillion miles, the Federal Highway Administration reported.

That's the fewest number of miles since Americans drove 2.890 trillion miles in 2003.

Meanwhile, gas prices rose last year.

The U.S. Energy Information Agency says U.S. gasoline prices are averaging $3.52 a gallon — up $0.38 over a year ago.

Drivers are also keeping their cars longer.

The average length of ownership of vehicles that were purchased new has risen to a record 71.4 months, or nearly six years, said automotive research firm Polk on Tuesday.

For consumers who purchased used vehicles, the average length of ownership is nearly 49.9 months. Combined, new and used vehicle owners are holding on to vehicles for an average of 57 months.

For new and used owners, the length of vehicle ownership among U.S. consumers has increased 23 percent since the third quarter of 2008, coinciding with the economic downturn.