The Finch Formerly Known As Gold

20 May 2004

Fluid dynamics

I reprint this item from On the Table at Autoextremist.com, just as a reminder:

Notice the hue and cry lately across all spectrums of the media from whining motorists who are shocked — shocked — that their various vehicles get worse mileage than the EPA estimates claimed they would? And the loudest whining seems to be coming from motorists who bought hybrids and expected the sun, moon and the stars from their vehicles — only to discover that they're getting much worse mileage than promised. Message to all offended motorists: Pay attention to the words on your EPA mileage label that says, "Your mileage may vary." Because it will, and it does. Then get over it.

There is, of course, the question of how quick I'd be to post this if I were getting lower mileage than the EPA estimates on my own vehicle.

Besides, the very nature of a hybrid makes it almost impossible to match the numbers on the antiquated EPA test. What's more, some vehicles have been tailored to get the maximum numbers possible on the test — some Corvettes "encourage" you to shift from first to fourth while accelerating.

But what do you expect? These are government-approved numbers; they'll never be better than "close enough for government work."

Posted at 10:52 AM to Driver's Seat


I'll bet most people would be surprised at how much they could improve their gas mileage by simply driving efficiently. Perhaps a public funded driver education course would do more to enhance our national security and energy strategies than anything else right now. And of course we'd need a catchy slogan such as "Driving Miss Iraq", "I can drive 55", or "Slow down for war". Uh ... something catchier than that.

Posted by: Mike at 11:52 AM on 20 May 2004

Except that the efficiency curve seems to vary with vehicle design. I drive the living whee out of my innocu-box, and I am rewarded for my profligacy with mileage better than EPA predicts. Meanwhile, other folks with the same model drive with the proverbial egg under the right foot and get 17 mpg and go back to the dealer and want to know why.

What this amounts to is: Know Thy Car. I know what works on mine. It might not work on some other model. (Another reason not to trade her in.)

Posted by: CGHill at 1:34 PM on 20 May 2004

They tell us anyone born in the USA can become president, too.

Terkish Payne, all you have to be is a white rich male that lies an awful lot. Michael Jackson is almost there.

Posted by: Terkish Payne at 4:35 PM on 20 May 2004

I figured out the hybrid/mileage thing back in 2001 when I was car-shopping. The hybrids that got all the fancy-ass mileage were the manual shifters; non-hybrid stickshifts also get better mileage. I looked up the figures on the automatic versions of the Toyota Prius (hybrid) and the Toyota Echo (non-hybrid) and they were the same. Only one was about ten thousand less dollars. I read that the weight of the battery pack (or whatever that thing is) offsets any mileage gains you might be expecting, and add automatic transmissions* in there and you will lose all the advantages you thought you'd gained.

*The automatic transmission in hybrids is some newfangled thing whose name I forgot and am too lazy to look up.

Posted by: Andrea Harris at 11:47 PM on 21 May 2004

Continuously variable transmission. An infinite number of ratios, over a range greater than is generally offered by the more conventional slushboxes. Theoretically, a CVT should be more efficient than the usual automatic and should approach manual-transmission efficiency, but "theoretically" doesn't translate well into the real world.

The spiffiest transmissions are the paddle-shifted manuals with automode that they bolt into Ferraris and the like. (Toyota did figure out a way to get one into the MR2 roadster, but Mister Two is more of a toy than any other Toyota.)

I have exactly one gee-whiz feature on my car: the center vents oscillate, just like a cheap desk fan.

Posted by: CGHill at 8:29 AM on 22 May 2004