If I draw 10 gallons of Shell V-Power out of the pump, I’m getting, give or take a tablespoon or two, 10 gallons; the Corporation Commission sees to that. After that, the laws of physics kick in, and internal-combustion engines are not exactly celebrated for their efficiency, which is one reason why electric-powered cars are selling in quantities no longer describable as miniscule.
Then again, if you draw 100 kilowatt-hours out of the line, how much of that is the car going to use? Here’s what one Tesla Model S owner found, after installing a digital submeter to determine exactly how much juice is leaving the outlet and going into the car:
[T]he Model S reported 728 kWh used during the period but the meter reported 894 kWh used. This means my charging efficiency is only about 82% and electric usage (and cost) is 18% higher than I may have expected based on the readings the Model S provides. For that month this is an extra $26 of charging cost which is a small number but a notable percentage of the total.
At his, um, current (sorry) electrical rate, he wound up using $143 worth of electricity for that month to drive 2,417 miles. At my around-town figure of 21.5 mpg, this means I’d be buying 112.4 gallons of gas to drive that same distance, and at last weekend’s fillup price ($3.299), I’m looking at $370 in fuel costs. So even if Tesla doesn’t win by as much as he’d hoped some electrics, he says, manage 90-percent charging efficiency it’s still a pretty substantial win.
(Via Autoblog Green.)