80 MPG Into the Wind

Craig Vetter's orignal purpose for selling the Windjammer fairings for Goldwings in the 1970s was to make the motorcycle both more aerodynamic and comfortable. Motorcycles are about as aerodynamic as bricks (yes, that's a cliche'), so very often they don't get much better mileage than a car. (Since most motorcycles engines/transmissions are optimized for power, motorcycles very often get worse mileage than cars.)

Since the 70s, motorcycles have only gotten heavier, in the same way that each revision of a particular car model is larger and heavier than the one that preceeded it. (This is why Honda now makes the "Fit" and Nissan, the "Versa": The Civic and Sentra are no longer subcompacts.)

The original Goldwing weighed about 650 lbs, which was huge for the time, but not uncommon now. It had a 999cc engine, again, huge for the time. The current Goldwing has an 1832cc engine and weighs about 900 lbs. Kawasaki and Triumph make motorcycle engines that are over 2 liters.

Because of this trend (and also because the manufacturers started making their own fairings, I'm sure), Mr. Vetter has become an idealist about aerodynamics. His current goal is to build a vehicle that will get 100 mpg at 70 mph, into a 30 mph headwind, and be able to carry four bags of groceries. He recently conducted a competition based on this goal.

His latest competition saw 5 vehicles, including Craig's streamliner, make a trip up the California coast. He wasn't too strict with the rules, however, as two of the five compitetors could not have carried the groceries. He determined the winner based on cost, which meant the highest mpg vehicle, a diesel, didn't win, because gasoline is currently cheaper than diesel.

The 125 mile trip from San Luis Obispo to Salinas saw fuel costs in the $4.50 range. (The stock Suzuki DRZ in the competition really didn't expect to win, and indeed had the highest cost at $8.49 and lowest mileage. The rider was simply there for the experience.) Vetter's own machine, a Helix scooter with a streamliner body, DNF'd when a fabricated gear shaft for the modified CVT broke.

Vetter has been expecting an engine in the 250cc range to work best, based on his calculations of the horsepower necessary to move a streamlined machine at the desired speeds. It's ironic, then, that the best fuel mileage was recorded by a traditionally styled motorcycle, one with a sport-style fairiing, but diesel powered. (This machine couldn't carry the groceries, however.) This Hayes Diesel motorcycle has a 670cc engine. Hayes already builds military motorcycles based on the Kawasaki KLR 650, because the Army wants one fuel for all vehicles in the battlefield and gasoline won't do. The civilian version in the competition will soon be on the market.

The result of this competition tells me that perhaps diesel is the best path toward fuel efficiency. The gasoline engined vehicles, even with far superior aerodynamics, got from 80 to 82 mpg, and the not-so-aerodynamic diesel, with an engine 2.5 times as large, got 89 mpg. Perhaps Mr. Vetter needs to put a diesel engine in his streamliner to see what it can do.