Isn't MTBE Methyl Tert-Butyl Ethanol???The secret is to get as many complex bonds to condition the fuel rather than explode. Tetra Ethyl Lead was an additive that slowed combustion allowing short chain hydrocarbons in higher compression fuel mixes without pre-detonating allowing longer chain hydrocarbons to burn at same time. TEL helped stabilize cracked long chains in synthetic fuels by giving longer shelf life...about two weeks!! Research numbers are results of comparing fuel explosions in comparison to pure octane (thought to be the ultimate "pure fuel" hydrocarbon). The single cylinder "engine" is fired and height of free piston determines the rating as compared to octane reading as "100". Since the tree huggers could not fathom the concept "octane rating" is now legislated. Try as they might, the environmentalists cannot seem to re-write the laws of thermodynamics. The primary difference of classic 60's Sunoco 260 and todays "Premium" is that modified long chain hydrocarbons aren't there. The fuel physically has less weight. More heat energy is produced and lost to engine and less energy is transffered to pistons. Miles per gallon have been sacrificed to butterfly breath. L. Andrew Jugle, Elmhurst,IL. To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/