Just got the Scangauge in today, and gave it a test spin in the 2006 Elantra. I really bought it mainly to watch the mileage. So far it works perfectly. Fits like a glove in the space below the radio, just have to figure out how to route the relatively thick wire. Hate to pull part of the dash on a ten month old car and drill holes. Yet.
Most importantly, the backlight color was easily adjusted to match the Elantra's green perfectly, looks stock. Unit is well made, display is bigger than I thought. Really big 'fonts'. Plugged it in, turned on engine, the Scangauge booted in about five seconds and was ready to go. Put in data on car engine, fuel tank, etc. in a couple of minutes or so. And that was that.
Went for a spin, set it to instant mpg, and watched as it read 0 mpg in the garage, then 3, 4, 5 crawling out the driveway and into the street. Then on to the store, where it merrily whizzed along from yucky low mpg accelerating to 60+ mpg when lifting off trottle. Average mpg to the store and back was 12. Hoho. Really makes you realize how miserable mileage is when braking, accelerating on short trips with stop signs etc.
Average mpg is similar to the readout on better Hyundai models, but is on another display from the instant mpg readout, so you loose the instant readout to see the average. Kind of disappointing to me but not a big deal. Nice selection of various mpg, fuel to empty, speed readings.
Most other readouts were fine but many redundant or boring, voltage, rpm, manifold temperature, etc. Like watching your cpu temperature and fan rpm's on your computer. Interesting for a second or two. But obviously important if at some point you need to analyze them.
Unit is very well made, all plastic but nice and substantial. Cord is six feet, enough for dash mounting but would be tight trying to loop it to an overhead windshield mount spot.
Manual was okay, but needs someone to edit it, put in some chapters, and move stuff around. Important first time fuel settings were twenty pages into the book. Manual on website easier to read.
White plastic buttons are really good for finding in dark, but they make the unit stand out when it's sitting in the dash. Kind of yells 'hey look do you want to break a window and get me I'm an add-on' kind of thing. Have to look into black magic marker or some kind of caps for them.
All in all for a one day test it's a very nice toy to help entertain, watch the mpg, and maybe come in handy one day if problems arise. I'm keeping it.