You're welcome. Its so hard to unwrap the myth from fact around fuels, and I am not that knowledgeable- seeing questions here prompts me to keep researching and passing on what I learn.

I do agree with Schwa. Detergent may not be bad, but plain 87 from Joe the (reputable) gasman is what the engine was designed for. Its what I use. Premium detergents can help...in certain cases (notice that the test procedures for TT gas start with a very fouled engine). You will not, however, see an MPG improvement unless the manual specifically calls for premium- and even then you may not get better mpg. I've got several tanks logged specifically to look for a change...nothing- maybe a bit worse mpg.

Looking through the EPA sample data, average fuel in many RFG areas already meets TT specs for sulphur, aromatics, olefins, etc, with the exception of ETOH if you live in an MTBE area. The car makers are striving to have a uniform gas spec nationwide because it will reduce their warrantee costs. There are many issues and compponents to what goes into fuel and why; detergents are a very small piece relative to things like GHG, smog precursor emissions, etc which are far more important IMO.

There is at least one member who, with very short drives and always-cold engines, has stated a pretty strong case for NOT using premium/detergent gas all the time under those conditions. He's wrecked 3 engines in fairly short periods with premium gas, according to him. I think what he says is correct, fo rhis particular situation.

And one of the major points of the TT slides I linked to was "marketing differentiation." Using subtle differences to set one product apart...aka marketing hype. Yes higher levels of detergent gas will help some engines (see test procedures), but a new engine properly cared for, using a variety of fuel sources (switch up your brands & stations) will very likely not have any issues at all.

Disclosure: I am a huge fan of ETOH as a supplement/replacement fuel. I think it should be marketed as such, and not as a magic elixr to solve engine woes.