Leave it to a knee-jerk Conservative (as Carl Sagan once aptly put it, "What exactly are Conservatives trying to conserve?") to see the highly intelligent effort throughout the world to phase out the combustion of a highly toxic heavy metal as some sort of anti-business conspiracy. There is no disputing the outright fact that lead is poisonous, and when one burns a liquid that contains lead, one releases highly toxic, extremely fine lead dust into the atmosphere. You'd be better off burning uranium dust into the air, at least that has a half-life, meaning it will eventually decay into something else.
Leaded gas destroys engine components. I guess that's helpful for the ever-precious economy, at least the automotive sector. Guess what? Most leaded gas engines can run just fine with unleaded gasoline (http://www.chevron.com/prodserv/bulletin/unld-gas/). Guess what? Ethyl alcohol is just as effective of an octane booster/anti-knock additive, and is just as cheap and easy to manufacture. The only reason ethyl alcohol was never used up until now is financial -- it couldn't be patented.
I'm not going to waste my time pulling up another cluster of references to "prove" that yes, lead is an insidious poison that has increased in concentration worldwide since the inception of leaded gas. I will tell you that since the decline in using leaded gas, ocean lead levels have dropped dramatically (http://web.mit.edu/newsoffice/tt/1998/feb11/lead.html) and human lead levels have dropped by nearly 80%, a change so dramatic that the makers of the additive attempted to sue the EPA to prevent them from even testing blood lead levels (http://past.thenation.com/issue/000320/0320lead-pr.shtml). Lead is a neurotoxin that does not decay. Unfortunately, Conservatives are profoundly capable of ignoring the precautionary principle, and are more concerned with their earnings right NOW versus the world's well-being later. Sometimes the health and welfare of the entire biosphere is more important than GM's quarterly earnings.
MBTE isn't the greatest choice of additive, either. Although little has been done to verify whether or not it has health hazards (still considered only a "possible" carcinogen), the EPA is considering setting standards on how much is permissible in groundwater. The MBTE molecule easily passes through the earth right into groundwater. Some aquifers are so polluted that cities have to pipe their water in from somewhere else. This has lead the State of California to completely ban its use, leaving ethanol as the only viable alternative. Although it hasn't been proven to be dangerous (like lead has), concentrations as low as 5 parts per billion can give water a turpentine-like taste.