A. Better check out her Harvard bumper sticker before saying anything. For there may well be a slight fuel-savings factor at high rates of speed, says Steen Sjolander, mechanical and aerospace engineer at Ottawa's Carleton University.
Air drag is at least partly related to surface frictions against the car body.
Streamlining helps, as when dust and squashed bugs are scrubbed away and small pits and scratches are wax- filled to reduce air turbulence and enhance efficient flow. Actually, surface finish accounts for only a little of this loss, with most stemming from the large turbulent wake behind the car, plus smaller wakes behind protrusions such as side mirrors. So the car washer who drives at German autobahn speeds might notice a small fuel consumption effect, but probably less than comes from keeping tires properly inflated. A. Try a placebo, the most potent drug known and with the fewest side effects, says Peter Smith, pharmacologist and neuroscientist at the University of Alberta. But you have to believe in it.