Is slowing up really that bad?

By Dave Churchill (Contact) | The Daily Journal

Published Friday, May 18, 2007

Like a lot of folks, the return of $3-plus-per-gallon gasoline has me thinking again about how to reduce my driving costs. Thinking about it, but not actually doing it yet.

It was a coincidence that I wrote a column about the topic a couple of weeks ago, musing about the benefits and drawbacks of driving 55 mph rather than the typical interstate speeds of 75 mph.

Seems like it is an idea that is worth thinking about, if the cost of fuel is really such a problem. The thought of going slower is, to be sure, rather irritating. But is it all that bad?

So it caught me a bit by surprise when I got a couple of rather vehement e-mails from people who had read the column on-line and wanted to explain how wrong (and stupid) I was for suggesting such a thing.

The potential for saving gas by driving slower undoubtedly exists. Although there are various estimates of how much it can help, one formula has it that a typical automobile engine loses 2 percent of its fuel efficiency for every mile per hour faster than 55. Driving 75 mph, then, would reduce fuel efficiency by 40 percent. That takes a car that would do 30 miles per gallon at 55 mph down to 18 mpg at 75 mph.

On a 240-mile trip, that’s 20 gallons of gas, or $60-plus at today’s prices.

Even if the formula for saving is half as beneficial as stated above, that’s still save $30.

Yet there are counter-arguments. What, for example, is your time worth? Putting aside the question of rest breaks, etc., it would take about an extra hour and six minutes to make the 240-mile trip at 55 mph.

And a lone-wolf 55’er faces some significant risks. No one expects to encounter cars driving that slowly when the speed limit is 70 mph. Do we really want some Suburban driver blasting up behind us at a 20 mph speed differential, at night, while chatting on the cell phone? Or worse, a drowsy driver of a big truck? The potential for disaster is obvious.

Some also cite the social cost: Poking along at 55 in the right lane is going to be a major irritant to all the other drivers on the road.

What the latter argument ignores, of course, is what would happen if we went back to the days of the 1970s when we the country actually got serious about saving fuel, and lowered speed limits everywhere to 55 mph. Then the only calculation is whether we can stand to spend some extra time on the road.

Of course, it is unlikely to happen, because it would be politically unpopular, to say the least.

Indeed, our efforts to becoming independent of foreign oil remind me a lot of our war against terrorism. While a few brave men and women fight and die for our country in Afghanistan and Iraq, the huge majority of Americans are utterly untouched by our so-called state of war.

It’s much the same with fuel conservation, except that in this case no one at all is sacrificing – although everyone is paying. There is lots of talk about improving vehicles’ fuel economy. There is some investment going into alternative fuels. But if dependence on foreign oil is a serious problem – and there is no doubt that it is, perhaps it’s time to act like it is a serious problem.

I would hate driving 55, after the luxury of doing 75. But there are worse things than getting there a little slower – such as running out of fuel entirely.

Dave Churchill is publisher of The Daily Journal