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"  According to the respected engineering firm, Ricardo, Inc, a proposed boost of ethanol from 10 to 15 percent in gasoline would mean &amp;quot;little, if any, change in the performance of older cars and light trucks, those manufactured between 1994 and 2000.&amp;quot; Note, this study was performed by Ricardo for the Renewable Fuels Association, a trade group working to influence the U.S. Environmental Protection Agency&amp;#039;s current considerations of a Fuels Waiver request to allow this increase in ethanol dose.   By way of background, most gasoline sold in the U.S. is already E10; the 10-percent ethanol originally added as an oxygenate helping older cars run cleaner. Those with oxygen sensors\u2014that is, almost all cars built since the 1980s\u2014derive no such benefit. More important these days, the ethanol serves as a fuel extender, 10 percent of such automotive fuel being derived from a renewable home-grown source.   E85, a blend of 85-percent ethanol/15-percent gasoline, takes this extender idea as far as possible (sans special cold-start enhancements that would be required in U.S. climates). Flex-Fuel cars, those capable of operating on E85, gasoline or anything in between, have dedicated fuel-delivery hardware and specially formulated tuning. This is necessary because, at high levels, ethanol is corrosive to many traditional automotive materials, seals, elastomers and the like.   A bit more background, this aspect frankly political: Government goals\u2014and subsidies\u2014of home-grown renewables have encouraged many into the ethanol business. Indeed, so many that there&amp;#039;s a current glut in ethanol. E85 continues to be something of a regional fuel, its widespread availability in the country&amp;#039;s midsection. Even there, price and mpg considerations compromise its popularity among Flex-Fuel drivers. And EPA&amp;#039;s current E10 Fuel Waiver places a &amp;quot;Blend Wall&amp;quot; on how much ethanol is needed for gasoline on a national basis.   Hence, EPA&amp;#039;s current quandary. On the one side, there are pressures to allow a 50-percent increase in the ethanol dose from today&amp;#039;s E10 to E15. On the other, automakers and others providing the hardware worry that vehicles not designed for this may suffer\u2014and they&amp;#039;ll be held responsible for any problems.   Also, ironically, many environmentalists question the food-versus-fuel aspects of ethanol-extended gasoline. Even the promise of cellulosic ethanol\u2014manufactured completely from waste renewables\u2014brings with it questions of water requirements in production, evaporative issues of clean air in use and ultimate mpg affecting its marketability.   Pure ethanol has less than 70 percent the energy content of gasoline. (And thus far its added octane is wasted unless exploited in dedicated ethanol powerplants.) As indicated in EPA mpg guides, there are considerable hits in fuel economy for Flex-Fuel cars operating on E85. As one example, a Flex-Fuel is rated at 22/33 mpg on gasoline, city/highway, respectively. Operated on straight E85, its corresponding ratings are 15/23 mpg.   E10 and E15 offer commensurate degradation in mpg as well, though their smaller hits are often overshadowed by inherent mpg differences of varying driving conditions.   More at issue is the question of E15&amp;#039;s added dose on vehicle durability. Initial research focused on E15&amp;#039;s effect on vehicles from model years 2001 and newer. Based on this, EPA appeared ready to grant an E15 Fuel Waiver specifically for these vehicles or, more conservatively, maybe even for those built after 2007. This Ricardo research, albeit performed for the Renewable Fuels Association, puts pressure on EPA to backdate E15&amp;#039;s apparent applicability to 1994. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.roadandtrack.com/car-culture/a16542/is-e15s-added-dose-of-ethanol-safe-in-your-car/>