How old is your car?

Are you still driving a mid- or late-Nineties model, or maybe one (like us) from model year 2000?

You're not alone.

The cars on U.S. roads have continued to age, meaning that the average vehicle is now older than at any time since the aftermath of World War 2, when U.S. manufacturing shut down for three years to build armaments.

According to research firm R.L. Polk (via TheCarConnection), the average age of a vehicle on the streets is 11.4 years.

And that's up from a startling 10.8 years old just last year.

Two factors have converged to produce this aging: One is the economic recession, the other increased reliability.

As any muffler-shop owner will tell you, there are still tens of millions of Americans who are keeping their old cars going for purely economic reasons.

"I have to get two more years out of it, so do the brakes, do the muffler, keep it going," is a common refrain, according to a mechanic we know.

But then there's reliablity: Cars are simply better built now than they were 20 years ago, with fewer failures and tougher components that don't wear out as quickly leading to longer on-road lives.

Our experience has been that when components do give up the ghost, it's due as much due to sheer age as to high mileage or overuse.

And that reliability means that cars won't suddenly get younger any time soon.

In a way, putting off those replacements for a few years will have a silver lining: New vehicles of all classes will get increasingly better fuel efficiency, owing to new and tougher corporate average fuel economy (CAFE) regulations put into place for 2012 through 2025.

For example, the average fuel economy of new cars sold in May was 24.8 mpg--a new high. And the numbers will only rise in future years.

Electric power plant outside Ithaca, New York

Electric power plant outside Ithaca, New York

Oh, and that argument about how you're saving energy by not buying a new vehicle?

A 2000 report from the MIT Energy Laboratory, On the Road in 2020: A Lifecycle Analysis of New Automotive Technologies, says that fully three quarters of a vehicle’s total carbon emissions come from the fuel it burns over its lifetime.

A further 19 percent is due to extraction, refining, and transportation of that fuel--and just 6 percent is from the raw materials and manufacturing process.

While more fuel-efficient vehicles may have changed those numbers, if you really want to save energy (if not up-front cash outlay), a new car will use far less energy to run than an equivalent old one.

How old are your cars? What's the oldest vehicle you use regularly (not including antiques or collector cars)?

Leave us your thoughts in the Comments below.

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