Sam commented, on December 6, 2007 at 9:15 a.m.:

CoolPerson Jenny wrote us to say:

I did an extensive research project on idling with an environmental law professor while I was an undergraduate, and the data on that is shocking. Although some sources, like the one you linked to, cite 30 seconds as the cutoff time, really anything over 10 seconds wastes more fuel, and produces more CO2 and other greenhouse gases, than restarting the engine. This is based on general use vehicles – sedans, minivans, pickup trucks, economy vehicles, etc. – and not large trucks or industrial use vehicles.

Also, as one of the sources you cited said, the only time cars need to idle is in sub-zero temperatures, and then only for a max of 60 seconds. Engines warm up best by slowly driving your car, even in extremely cold temperatures. Thank you also for pointing out that in addition to wasting oil and polluting, idling also increases wear and tear on the engine and its parts. This costs the trucking industry millions each year, which is one of the reasons why they have been the most proactive in investing in non-idling power technology and creating rules against idling for truckers and truck tops. Canada is also really progressive on this issue, as might be expected due to their cold weather and thus increased rate of idling.

We also found that if drivers in the U.S. could be persuaded to cut idling time to 30 seconds while warming engines or waiting in non- road situations, this could save 21.1 million tons of CO2 each year.

No one seems to know this, though! Sometimes, if it is a safe situation, I will politely let drivers know, but usually I just get blank stares and “why the hell do you care” looks. Oh, well. Thank you for helping to spread the word through CPC!! I am continuously impressed by the quick and info-packed emails.

DEBI commented, on December 18, 2007 at 1:01 p.m.:

WOW I wish my next door neighbor would read this. Every morning at 5:00am he starts his car at lets it run for at least 30min, of course he doen't have a car that is quite, it has a muffler that vibrates our windows. I don't know if he is mad because he has to leave for work so early and figures if he is up the whole neighborhood will get up too or if he really doesn't care.