IT Career JumpStart

Aug 12 2009   7:01PM GMT

Hmmm! What does “230 mpg” really mean?

Ed Tittel Ed Tittel Profile: Ed Tittel

In looking over the Larry Dignan blog for SmartPlanet, I find the headline “Chevy Volt: 230 mpg in city driving: $2.75 per 100 miles…” tantalizing at first, infuriating as I read on and discover the basis for the mathematics. This is only the charge for gasoline in a car that drives 40 miles on stored electrical power alone, and fails to include the charges for powering up the battery in the first place.

I don’t know where Larry lives, but in my part of the world, electricity is pretty expensive. Austin Energy, for example, charges $6 per month, plus 3.55 cents for the first 500 kWh, and 6.02 centers for each additional kWh over 500 from November through April, and 7.82 cents for each added kWh from May through October, not to mention the fuel adjustment charges that kick in. According to, for an example, the 2009 average for Texas electricity is about 9.16 cents per kWh including all charges.

This all goes to show that when you decipher claims about performance, it’s essential to understand what’s being measured, and how related measurements are taken. While the old adage “you can’t monitor it, if you don’t measure it” remains as true and important as ever, it’s still important to know what’s being measured (and in this case, upon closer investigation) what’s not being measured as well.

Ultimately, the old IT acronym TCO (Total Cost of Ownership) will come into play for the Chevy Volt, as it does for all motor vehicles. Only then will we really understand what the $40,000 price for the vehicle actually pays for, and what other costs must be incurred to operate this vehicle over time and distance for commuting, travel, and so forth. Whatever those turn out to be, this promises to be a fascinating phenomenon to observe, and from which to learn.

Maybe we can start making similar claims about the Internet for miles per kWh. In that case, I’m sure the Internet will leave the Chevy Volt far, far behind!

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