Here's a short demo of Rev app in action on the G35 allowing to view real time OBD II metrics. You can also record and export your data and customize your gauges.
My G is mostly stock besides stillen intake and reflash of the ECU and Motordyne plenum spacer on the way. Check it out:

 

Thats nice but it still doesn't make that thing mounted on there look any less hideous.

 

whats up with those numbers? like 0-60/whp

 

it said 194whp on your car? dont think thats right.

 

Let's say I'm lazy one day and don't connect my ipod. Will it pull info off the OBD later (for instance, to keep the MPG accurate)?

 

I havent pushed it to the limit thats why youre seeing those numbers i just got this app the other day so im still working the details out and its whp power so i should be around 240whp. Maybe i got the weight of the car wrong. The curb weight is around 3800 but does that account for the weight of the driver, because torque and hp calculations take into account weight?

 

Cpufreak if im not mistaken the app syncs your previous mpg avgs

 

Either way if your doing it through wifi it will still lag a bit. You can also do it through bluetooth through your phone. I have an OBD2 that i ordered and hook up to my laptop.

 

Well what I mean is does the kiwi store anything?:

Day 1: connected, and I'm getting 15 MPG
Day 2: not connected, and I'm theoretically getting 20 MPG
Day 3: when I connect, will it pull info from the kiwi and show 17.5 MPG

Or will it only show 15 MPG? Essentially, does the kiwi store anything?

 

Nope kiwi does not store