G-Tech Pro for $49.95 on eBay

[Justin McClanahan]

It is as accurate as your installation/placement on the
windsheild. The newer one, with multiple sensors, is more
accurate in general because it takes the installation
error out of the equation. The G-tech Pro is supposed to
be in the center of the vehicle pointing straight back,
and then have it zero'd out horizontally on level ground.

Justin McClanahan

> Anyone know how accurate this thing really is?