It's easy to calculate that a car with the engine running but not moving is getting zero mpg. New technologies allow some cars to take control of the on/off switch from the driver when stopped. Whatever their name - stop-start, micro hybrid - automatic systems that shut down a vehicle's engine when the car is at rest help boost efficiency. Automakers - especially in Europe - are happily introducing the technology to vehicles like the Fiat 500 to the Audi A4 and A5 to Ford vehicles that will get the new 1.6L EcoBoost four cylinder engine to every Mercedes. But here's a question: just how much fuel does idling waste? While the exact amount is determined by the size of your engine, there is a specific amount of time that most sources say should be the idling limit. How long is that time? Take your best guess in the poll below and then follow us after the jump for the answer.

It would be better to shut off the engine if I'm going to idle for more than...
1 (12.5%)
1 second 1 (12.5%)
2 seconds 1 (12.5%)
5 seconds 1 (12.5%)
10 seconds 1 (12.5%)
20 seconds 1 (12.5%)
30 seconds 1 (12.5%)
60 seconds 1 (12.5%)

[Source: Vanderbilt Lawyer, Green Car Advisor. Image from Canada's Idle-Free Zone campaign]

A recent survey by the Vanderbilt University Climate Change Research Network found that, for the whole of the U.S., drivers who let their cars and light trucks idle (at places like drive-thrus, bank lines, driveways, etc.) "account for 17 billion pounds of carbon dioxide emissions each year." In fact, idling makes up about 1.6 percent of America's mobile and stationary pollution, says Green Car Advisor.

As for the poll, the correct answer is ten seconds. That's what we found that over on the Vanderbilt page as well as on Treehugger and a bunch of other places.

I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.

    • 1 Second Ago
  • 2015 Toyota Highlander
    MSRP: $29,765 - $44,140
    2015 Jeep Grand Cherokee
    MSRP: $29,995 - $64,895
    2015 Honda Accord
    MSRP: $22,105 - $33,630
    2015 Honda Civic
    MSRP: $18,290 - $26,740
    2015 Mazda Mazda3
    MSRP: $16,945 - $25,545
    Share This Photo X