This is true, but not necessarily due to the ignition temperature. From my understanding, if the timing isn't optimal with 87 regular, moving to a higher octane rating gas may allow the engine to advance the timing. A friend of mine with a 2001 Protege ES 2.0 had quite a discussion about this on a different board. 87 was recommended for his car, but he switched to 93 (I forget why exactly) and noticed a difference after 50 miles or so. Obviously, it won't make a difference for most engines, and putting 110 in a Focus that's NA and barely tuned would be stupid.Then in theory if you could use 89 octane and not have detonation at the same timing that is in our cars, you would have a slight increase in power because the fuel would burn hotter. Is that what I am taking from this too.