Based on members’ suggestions, I have added two questions to the Fuel Economy Survey. One asks about the amount of time spent idling after a cold start, the other asks about the distance driven between cold starts. I was initially reluctant to lengthen the survey, because the shorter it is the more people will participate. However, some research found that both members’ cases were too strong to ignore.

Doug and Josh pointed out that people with short commutes will observe much worse fuel economy, because cold engines burn more fuel, and these people do most or even all of their driving with a cold engine. Definitely true, but how many people have short commutes? I guess we’ll find out.

Once I decided to add this question, I had to decide how to word it. Just have people type in the length of their commute? Many people probably don’t know, and thus would simply not respond. Let them choose from a few ranges? Better, but which ranges?

Luckily, I came across a chart of commute length by fuel economy. It shows a steep gain up to about two miles, then a leveling off around 5.5 miles. So I decided to go with three ranges: less than two miles, between two and five miles, and over five miles.

The question also asks about the distance driven between cold starts rather than commute length, because some people don’t have commutes per se, and the real issue is how much of the driving is done with a cold engine. A few short drives spaced close together aren’t the same as a few shorts drives a day apart, as the engine doesn’t cool all the way down in the first case.

The second new question was inspired by Dennis, who pointed out that people with remote start, an increasingly common feature, often start their cars 5 to 10 minutes before driving off. Unllike commute length, I hadn’t thought of this at all. Do people really do this? To find out, I posted questions on a couple of forums (GMInsideNews.com and SaturnFans.com). Turns out that this behavior is common.

Of course, regular old “warming up” by idling in the driveway or garage has the same impact. So the question asks about how much time was spent idling. To keep things simple (for U.S. participants, anyway) this question uses the same ranges as the other new one, just with minutes rather than miles.

In both cases, the survey asks about “most days” during the tank. Clearly, these behaviors can vary from day to day, just like those covered by the existing questions. So responses can rarely be exact. But as long as people provide their best guesses (for all but the fuel economy figure), it should all come out in the wash of stastical analysis. Just need enough responses…