I interviewed the inventor a while back. He described 3 main markets:
- Traditional gearheads: Ron explains, "these are the guys who in the old days used to install extra gauges on the dash that gave more info than the idiot lights could." Typically "performance" (speed) oriented folks, these DIY types want to know everything the car is doing when it's being pushed hard.
- RV owners: these people have a kind of mixed interest. The engines in their (typically heavy, un-aerodynamic) vehicles also tend to get pushed fairly hard, so the drivers want to keep an eye on critical info. At the same time they're also concerned about fuel economy and want to monitor that as well.
- Fuel economy nuts: these are the MPG obsessed folks (you know who you are) who, prior to the ScanGauge, had to rely on infrequent fill-ups, or relatively crude vacuum gauges for feedback on driving technique or changes made to their vehicles.
From:
http://metrompg.com/posts/scangauge-interview.htm
Though with the recent run in fuel prices, and free advertising the SG has had in the mainstream media, I think the fuel saving crowd is their biggest market now. Based on the fact they never had an order backlog before $4 gas.