Annals of Delusion: CNG and Mini Cars

If you’ve been following this site, you know that it is a core DbC thesis that automobiles are far closer to their right walls of perfectibility than their sponsors admit or the deluded fans of alternative fuels understand. 100 MPG is simply never going to happen in any car, regardless of its power source, that’s viable in sprawling, cars-first-transportation conditions. The laws of physics forbid it.

To wit, two pieces of news today:

According to this story in the online version of the Albany Times Union the compressed natural gas Honda Civic gets “38 mpg highway, 27 mpg city.” Converting cars to CNG, in other words, would burn up natural gas at the same rate as the better petro-cars now burn oil. Hardly a potential rescue for the status quo.

Meanwhile, here’s why physically tiny cars aren’t as fuel-efficient as you might expect:

NEW YORK (CNNMoney) — When most people look at really tiny cars they figure they must get really good fuel economy.

And when compared to trucks or family sedans, they do.

But subcompact and mini-cars — the likes of the Fiat 500 and Chevrolet Sonic — usually don’t get much, if any, better fuel economy than roomier compact cars.

For instance, at 33 miles per gallon, the most efficient version of the subcompact Chevrolet Sonic gets the same overall fuel economy as the larger Chevrolet Cruze Eco compact car. Other versions of those two models differ by only small amounts in combined city and highway driving.

Same for the teeny Hyundai Accent versus the larger Hyundai Elantra. Again, both get 33 mpg in combined city and highway driving. The subcompact Ford Fiesta actually does get better mileage than the compact Ford Focus. But the Focus, with 30% more horsepower and 43% more cargo space, gets beaten by just two miles per gallon.

It’s even true of hybrids. The tiny Prius C gets the same overall fuel economy (city and highway combined) as the larger Prius. Both are rated at 50 miles per gallon.

What gives?

Aerodynamics, mostly.

No matter how small it is, a car still has to hold people inside comfortably.

“You can shorten it up and make it narrower, but the height of a car can only be so small,” said Scott Miller, director of mass, energy and aerodynamics at General Motors, which makes the Sonic and the even smaller Chevrolet Spark, due out soon.

That means that, once you get past compact car size — the size of an Elantra, Cruze or Focus — cars start looking like tall boxes on wheels.

That’s not the best shape for pushing through the air. Slightly larger cars allow designers to refine the shape to better control airflow around the vehicle. Small cars provide less sheet metal to work with.

Vaporware Update: Cellulosic Ethanol

gas cliffSeems the United States is currently producing zero gallons a year of cellulosic ethanol.  This, despite the assurances of hyped “entrepreneurs,” hundreds of million of dollars in subsidies, and a 2007 federal mandate for production of 100 million gallons a year by 2010.

For more, see this story by Robert Rapier.

Rapier’s conclusion?  Will-power is not enough to alter the laws of physics.  Cellulosic ethanol will never be more than a niche fuel.  The wish that it would run the cars-first transportation order of the United States?  “Fairy dust.”