The U.S. economy, in one chassis. (Tomohiro Ohsumi/BLOOMBERG)

Vehicle purchases by consumers alone accounted for 30% of all the GDP growth in the last two quarters.

Cars are, ahem, driving the recovery. But will it continue? Auto analysts are expecting another record month of car sales in May: announced today that it was predicting the highest monthly level of vehicle sales since 2007, up 32 percent since this time last year.

What’s striking, though, is that auto sales this year are still expected to be way below the long-term average for the 2000s. (About 14.5 million units vs. 16.6 million.) Unless Americans are planning to give up driving en masse, that suggests there are still a whole lot of vehicles out there that are rapidly aging and eventually need to be replaced.