So myself and Si both have it, and Ger's in the middle of getting it. I had my first play with Dynolicious last night. The cost for the app is a very reasonable €10.30 and installs through the Appstore on your mobile device.
After the initial loading of the app, it brings up a huge warning telling you not to do your testing on public roads, be careful of children, and chew your food 32 times before swallowing. The usual nonsense disclaimers. The app then needs you to setup your car. You give it a name, type in the kerb weight, and the drivetrain loss between the flywheel in the engine, and the wheels itself. After that, you can run your initial test.
The accelerometer inside the iPhone works brilliantly for this test, but it has a few basic requirements. The designers say it doesn't matter if it's pointed lengthways, or crossways, but it must be perpendicular to the angle of direction, if the phone is rotates sideways, it won't work. They recommend just sticking it into a Cup Holder and working like that. In the real world, I'm not so sure. I did a few tests last night, and I found that when it was just in the cup holder, the results weren't so great.
On my first run, it gave me a horsepower figure of 140hp (Not Bhp), and a 0-60 of almost 9 seconds. Mostly because the road was wet, and the traction was fighting to stop the wheels from spinning. Second run gave me 160hp (About 180bhp), and a 0-60 of 7.5 seconds. Still not great, the traction control was still fighting to get the power down on the wet roads. As you're driving, it is plotting the graphs in realtime for G force, Hp, and Speed. It's very much a real dynograph sensation, and it breaks down the whole test into detailed statistics when you're finished, including 0-10, 0-20, 0-30, etc, maximum hp, maximum G force, and total test time/terminal speed.
There's also a skid pan screen, where you can just sit the phone in the cup holder, and it'll tell you lateral (Sideways) and directional G forces, for both accelleration and braking.
Overall, it's a very good app, and well worth the money. I can't wait to try it at the Cork 100 run in Watergrasshill and get some real world figures without having to observe the national speed limits, etc.