The good news is that cars and trucks in the United States have been getting much more fuel-efficient in recent years. The bad news is that gas prices are rising so quickly that Americans are now spending a bigger share of their income on gasoline than at any time since the early 1980s.

That's according to a new report from the U.S. Energy Information Administration, which found that the average household spent nearly 4 percent of its income on gasoline in 2012, the most in nearly three decades:

Here are some numbers from the EIA — Americans are using less and less gasoline, but they're paying more for the gasoline they're using:

Efficiency gains have accelerated in recent years, such that total U.S. gasoline consumption fell in 2011 to 134.2 billion gallons, its lowest level since 2001. However, at the same time, EIA's average city retail gasoline price rose 26.1% in 2011, and another 3.3% in 2012, when it reached $3.70 per gallon. The effect of the higher prices in 2011 and 2012 outweighed the effect of reduced consumption.

To look at that another way, the average vehicle owner is now likely to spend nearly as much money on gas as on the vehicle itself. That's according to a separate study released by the Union of Concerned Scientists, which found that "a typical American driver will spend more than $22,000 on gas over the lifetime of a vehicle purchased in 2011 with average fuel efficiency (22.8 mpg)."