I would never own a motorhome or truck without a Scan Gauge. I've had mine for 11 years, bought it for my 5.4L V-8 F-150 when I was towing a 22' TT. When I bought the Class C I just reprogrammed it for the 6.8L V-10 and have not looked back. The install was all of about 4 minutes, two small pieces of velcro and a wire tie for the excess coil behind the dash. It just does not get much simpler than that.
For the record I always run with average and real time mpg's displayed along with transmission fluid {X Gauge function} and coolant temp. The first trip I took with the SC I got 10 percent better mileage just by watching the displays and playing the game of trying to keep my real time mileage higher than the average. I figure I got my $139 back in about 6 months just on fuel savings.
:C