For my last 5 tanks I've kept the instantaneous mileage gauge permanently switched to engine temperature because I kept focusing attention on it instead of just enjoying the drive and looking at the scenery. I'd go for a drive and then realize I never saw anything since all I did was watch the gauges.

I do keep my trip mileage displayed, and I look at it fairly often, but I have no problem with it and it's not distracting.