cam timing
 

I am sure this topic has been hashed around, but for a single cam engine:

Which would get better mpg, advancing cam timing or retarding cam timing.

Advancing cam timing will make the engine have the lowest brake specific fuel consumption at a lower rpm, so one can drive in a higher gear.

Retarding the cam timing will cause some of the mixture to be pushed back into the intake manifold, thus lowering the pumping losses. The exhaust valve opens later, thus providing some extra force on the piston.

It seems to me that for lugging around town, an advanced setting would be better and for highway a retarded setting would be better.

Anyone have experience?

I have an 09 Denali. I have been playing with the tune. I can tell you that with my L92 VVT motor (cam advance and retard) at cruise, the cam is retarded. I get right at 19mpg highway which is pretty good for a 5600+lb box that is AWD and has over 400hp. Of course I am on eco modder looking for more.