We’d save much more fuel by improving the efficiency of our existing fleet than we will by attrition. And do it faster too.

Our population is getting old, slow, and lazy. What people need to remember is that slow does not equal efficient. (Fast can also be inefficient; when it’s sloppy and reckless.)

What Zero Growth Advocates don’t want you to know:

Faster acceleration is not significantly less efficient than slow acceleration. In fact, it’s generally more efficient, even before considering that it prevents, and speeds the clearing of, congestion and bottlenecks.

A car engine typically produces power most efficiently at about 3200RPM. It most efficiently delivers power to the road at about 2100RPM. But, more importantly, increasing the power delivered doesn’t decrease efficiency much until higher RPM, closer to 4000RPM. Gas consumption is actually lower at higher load and engine speed than at the low engine load and slow engine speed of gradual acceleration. (see Brake Specific Fuel Consumption)

Engines deliver power best at two spots. At low RPM and very light loads, such as for maintaining speed, and at higher RPM delivering larger loads, such as for more rapid acceleration.

And higher cruising speeds are actually more efficient up until aerodynamic factors dominate at about 55MPH . (see EPA Fuel Economy tips and MetroMPG.com post Speed kills: testing MPH vs. MPG in top gear )

Some observations that should put things into perspective: Driving increased pretty steadily until leveling off in about 2005. It peaked in Oct 2007, before prices spiked in spring 08. Despite the flat trend in driving, our fuel consumption continued to increase. You read that right. Fuel economy declined starting around 2005, despite our improving fleet fuel economy rating and no big increase in the amount cars on the roads (prior to then, fuel economy improved despite the great popularity of trucks and SUVs). Fuel economy didn’t rebound until the gas price spike in 08 drove poor, stupid and slow drivers off the roads (Sorry about the pun. I didn’t mean for it. Though I must admit, I like puns.)

So long as people believe slow is efficient, high gas prices will decrease our fuel efficiency and waste our time. (Except when lack of an economy leaves our roads empty and free flowing.)

What I’m suggesting is not aggressive driving. Aggressive driving is defined as rapid acceleration and braking. What I’m suggesting is that people should drive with ambition, with purpose and attention. By looking a head, drivers can make adjustments to speed using the accelerator pedal rather than the brake. With electronically controlled fuel injection, when cars are moving they can keep the engine turning with little or no fuel. It’s actually the braking that wastes fuel, not the rate of acceleration.

It’s not our desire for more power that has kept fuel economy from improving. It’s demanding more power, but failing to make use of it.

People need to act with purpose. It’s when we’re constrained from acting meanifully that ambition turns into agression or we turn to dangerous distractions like phone calls, texting, drinking, and day-dreaming.

Fat, slow, poor, and stupid is no way to go through life, it’s now way to run an economy, and it’s no way to prevent global warming.