I have an Ultragauge. Its pretty cool if you are really into getting the operational info on your vehicle. I use it for Oil Distance to Change (settable in 1500 mile increments, I think), Gas Distance to Empty (make sure you reset it at every refill), Avg MPH, Immediate MPG, and a few others I can't think of right now. They are MANY different parameters it can report on. And it can read and reset all OBD-II codes, but not trans codes. All in all a pretty cool doo-dad, but you could probably live without it. The Support page on ultragauge.com has the manual you can download for free, fyi.