that MTBE can actually harm fuel system components in older cars such as floats, float needles, some rubber components.

It can also reduce fuel mileage in most newer cars because the engine runs leaner, the computer compensates by increasing the amount of fuel in each injector shot therefore putting more overall emission out the tailpipe.

The same effect makes older, carbureted cars run lean which can INCREASE carbon monoxide levels...not to mention drastically reduce engine life.

I'll see if I can find the article I read on this recently.