The competition in the heretofore unknown "iPhone dyno app" market is heating up: Liberty For One is attempting to one-up BensenTech by releasing its own automotive measurement tool, called g-tac, for just $4.99, Autoblog reports. As with Dynolicious, g-tac also measures quarter mile trap speed, 0-60, and 60-0 figures, and uses the iPhone's accelerometer so you don't have to connect anything to the car.

However, the report said that g-tac's feature list doesn't appear to match Dynolicious, which also features metrics for lateral Gs and engine horsepower. Plus, early user reviews in the App Store seem to favor Dynolicious over g-tac. Any readers with an iPhone and a taste for running their car at ten-tenths? Let us know in the comments section below. (And please confine any performance testing to a racetrack or other non-public road.)