One of the things that is getting a lot of lip service currently is the use of alternative fuels to power cars and trucks that normally run on gasoline—so called flex fuel vehicles (FFVs). The most common “flex fuel” is E85 ethanol, a mixture of 85% ethanol and 15% gasoline. The trouble is FFVs are gas guzzlers in green clothing.

Recently MotorWeek, the automotive television magazine from PBS, tested a number of new “green” autos and trucks. Among them were two versions of GM's popular Tahoe SUV: one the new “2-Mode Hybrid” model and the other a flex fuel model. These are large, American size vehicles each weighing in at over 5000lbs. In fact GM described its new Tahoe hybrid, the company's first full hybrid, as a “big ass hybrid” in a promotional video.

Unlike the normal compact and economical image projected by other hybrids like the Toyota Prius and Honda Accord, GM is promoting these hybrids as big, powerful machines. The Tahoe is the heaviest car GM makes, despite making the doors and hood out of aluminum, and the hybrid version even has a larger engine than normal. How do the big ass hybrid and flex fuel Tahoe perform? To quote from MotorWeek:

“Until now, we would never use the words Tahoe and fuel efficient in the same breath, but that was before GM's new 2-Mode Hybrid system was placed under the hood. On our test loop, we achieved 21 miles-per-gallon in the hybrid and 19 in the standard Tahoe, burning gas. A separate loop in the same truck with E85 in the tank returned no better than 14 miles-per-gallon. The gap was much wider in city-only driving, with the hybrid holding an advantage of 8 to 12 miles-per-gallon over the FFV.”

The thing that should standout among these mpg figures is the dismal 14 mpg for the FFV running on E85. That's right, the mpg when running this new FFV on ethanol simply sucks. Why? One of the downsides of burring ethanol is that, volume for volume, it contains less energy than good old gasoline—what engineers call lower energy density. The energy content of ethanol relative to gasoline goes like this:

A. 76,000 = BTU per gallon of ethanol.
B. 116,090 = BTU per gallon of gasoline.
C. 0.655 = 2/3 = GGE of energy in a gallon of ethanol (A / B).
D. 1.53 = Gallons of ethanol with the energy of 1 gallon of gasoline (D = B / A).

There can be some minor impact due to engine tuning that affects this energy balance but the plain truth is that any FFV will get poorer millage when running on E85. The EPA tested the gas mileage of the flexible fuel models available in 2006. For the 31 models they tested the average reduction was 26% fewer miles per gallon. For example a car that gets 30 mpg on regular would typically get 22.2 mpg with E85—exactly what is predicted from the fact that E85 has less energy per gallon than gasoline. This is further complicated by the difference in price per gallon of the two fuels.

The party line is that E85 costs less than gasoline but, even though ethanol production is heavily subsidized by the Federal Government (meaning all of us), the reality of the pricing situation is not always what is claimed. In the 2006 calculations mentioned above the EPA assumed that E85 cost $2.00 and regular gas $2.20/gallon (don't we wish this were true today). 0n average the EPA estimated driving on E85 would cost 23% more than driving on regular—a figure that holds true today according to MotorWeek.

Calculating fuel-cost-per-mile, the Hybrid Tahoe leads with a figure of 18.3 cents, followed by the Tahoe FFV running on gasoline at 22.9 cents and trailed by the FFV on E85 at 27.7 cents per mile. Running the Tahoe on E85 will cost you 21% more per mile than gasoline and a whopping 51% more than the gas-electric hybrid. Of course the point of all this hybrid and flex fuel technology isn't just to save energy, we're also trying to save the planet. In what seems a green victory, emissions test shows the E85 Tahoe is cleaner than gas or hybrid overall. But, if you believe the greenhouse gas global warming hype, the evil CO₂ emissions of the hybrid are markedly better than those of the FFV on E85, despite its bigger 6.0 liter V8.

Add to the poor mileage and lower energy density the meager energy yield of ethanol—only about 30% of the energy in ethanol produced from corn is new by most estimates—and the promise of ethanol dwindles to near nothing. In fact, biofuel production may be harming the environment. The "dead zone" at the mouth of the Mississippi River has grown in size in recent years with many researchers blaming the growth on increased agricultural run-off, run-off that can be linked to additional crop production for use in biofuels. “Levels of nitrogen in Gulf waters are especially high in the spring and summer, when fertilizers are most frequently used,” reported Texas A&M researcher Antonietta Quigg, in an article in LiveScience. “We still have a lot of work to do, but it looks like fertilizer runoffs remain the culprit in helping to create this large dead zone.”

So what's the point of all of this? That many of the things being pushed as more environmentally friendly or more energy efficient by politicians, the media and the eco-lobby simply aren't. Just as the push for biofuels in 2006-7 only led to higher food prices, riots in Mexico and dead fishing grounds at the mouth of the Mississippi, the promise by some politicians to make “every new car a flex fuel vehicle” is just so much flummery. As usual, politicians say what they think will get them elected, not what is best for the nation. Hybrid vehicles, and in particular plug-in hybrids, are the real champions here—accept no substitutes.