New SAAB Turbocharger Gets More Mileage, Performance from E85

The New turbocharged SAAB gets more power out of E85 without lowering miles per gallon by taking advantage of a high octane rating, increasing the comression when using E85. This kind of technology, if widely implimented by car makers, could improve the economic viability and net energy balance of Ethanol.
Liquor Does It Quicker - Popular Science:
by Matthew Phenix -- July 2005

E85 typically delivers inferior fuel economy; it has about 75 percent of the potential energy of gasoline, so it takes up to 20 percent more hooch to keep horsepower on par. But E85 also has a high octane rating (around 110), and Saab realized that a turbocharger could harness it. Turbos push extra air into the cylinder, and higher octane allows a fuel to better endure the increased pressure. So Saab cranked up its fans and created the BioPower engine, the first commercially available ethanol turbo. A computer samples the fuel mixture and adjusts boost pressure -- from 5.8 psi for pure gasoline to 13.8 psi for E85. Running straight gasoline, the engine produces 148 horsepower, but E85 jacks it up to 184, with no penalty in fuel economy.