Why not drive 55?

As I mentioned (rather in passing) in an earlier post on the latest energy company porkfest, despite Bush's declarations to the contrary there are things he and Congress COULD do now to immediately reduce US gasoline consumption, and therefore gasoline prices, one of the simplest being to declare a national maximum speed limit of 55mph.

But then I got to thinking, especially since I enjoy driving as fast as any other red-blooded Angelino, would 55mph really help?

After a quick Google I've found, to no great surprise, that the question was indeed subject to debate.

The main arguments against seem to be 1) anecdotal accounts by individuals claiming they get their best mileage at the 70-75mph range, and 2) arguments the 55 is simply unenforceable.

As far as the anecdotes go, I strongly suspect that the individuals were getting their best mileage because they were going highway speed, which just happened to be in the 70-70mph range.

An informative article at howstuffworks.com would seem to bear this out:

" So, for most cars, the "sweet spot" on the speedometer is in the range of 40-60 mph. Cars with a higher road load will reach the sweet spot at a lower speed.
…
If you drive your car in the "sweet spot" you will get the best possible mileage for that car. If you go faster or slower, the mileage will get worse, but the closer you drive to the sweet spot the better mileage you will get."

Be sure to read their reasoning and analysis, but it seems pretty accurate to me.

As for the enforceability issue, my thought is that the goal is to influence mass behavior rather than individual behavior. That is, though individuals will continue to flaunt posted speed limits, as they have ever done, anything that drops the average highway speed of the millions of US drivers has a value, especially given the efficiencies seen with every single mph dropped (again I'll refer you to the howstuffworks article).

The main problem with 55 seems to be symbolic: it smacks of the bad old 80s oil embargo and Jimmy Carter's presidency. "Malaise" anyone? And though my inclination personally would be to defend Carter's presidency and legacy, I have serious doubts as to whether the Republican controlled Congress or White House would be so inclined.

More's the pity.