I had one in a 4x4 and yes they do work as I found out the hard way when we ended up wheels pointing to the sky after a speeding drunk driver ran a red light and T boned me at a intersection, whilst I was hanging upside down held in by the seat bets I did notice the inclanometer was reading correctly.
But as a more useful adition I was given one that has a GPS spedo and a compass as well as a three access inclanometer as well as an altimiter digital compass coordinates read out and temprature gauge, that I fitted to my CAT Backhoe , I found the altimiter a great bonus knowing the height of a hill and the distance from top to botom and it's fairly accurate comparing it to a theolodolight and range finder one would normally use, the speedo not so good as it only starts reading speed at 5kph but is accurate after that great for on road travelling as the back hoe dose not have a speedometer or odeometer, It plugs in to a USB port that comes with the 20w solar pannel I mounted on the roof of the cab to keep the battery charged, it was bought on E-BAY for around $30 Au to mount on an old 4x4 quad bike atv type of thing that is now dead.
I wouldn't ever have thought about fitting one of these things, as a back hoe owner and operator you soon learn the limits of the machine without an inclanometer, use your own pucker gauge,and check where the inclanometer is, for the price and extra features far more usefull on any tractor I might get one for my ride on mower it would be interesting to see how much milage it covers doing the mowing.
