Mine has a lag.
When I come to almost a full stop and the go again, I hit the gas its dead for a secong then jumps.
They said there was nothing wrong, then I went to get snows on and complained again, so they said I had a streched timing chain and they kept it for 3 days and did $4k of work under warranty...now its no different.
I really dislike driving with that lag...quite annoying
PS as far a mileage, I go with the old adage...if you have horses, you gotta expect to have to feed em