Thanks a lot, Phil, for great contribution to the community as always and please count me in!
Suggestions:
1) Phil, not sure if you have finalized hardware design but how about using Raspberry Pi ? http://www.raspberrypi.org/" onclick="window.open(this.href);return false;
For the cost of $25 - $35, it is offered as a full computer with Debian Linux with 2 usb input ports. Maybe Leaf instrumentation data can be fed through the USB ports. Not sure if your hardware cost would be lower than that. For display it can output on HDMI port or TV output. It would still need to be enclosed in a display (unless it is connected to a smart phone). But, this is just a thought.
2) While I agree with your points about not having to rely on a phone app connected by bluetooth to LeafScan, I think there is reason to allow both (i.e. dedicated display and a few buttons on LeafScan for basic operation as well as a smartphone app). So, LeafScan would be great for basic interface but since Leaf instrumentation may have lot more data and lot more settings than can conveniently fit in little LCD of LeafScan. Also, with lot more settings and parameters, it would require more UI and more buttons on that small device. Dedicated hardware of small non-touchscreen display with a few hardware button might become limiting factor at some point in future whereas smartphone touch screen interface is easy to modify with only software change. So, there is value in having an Android App that can connect to LeafScan over bluetooth for more sophisticated UI, charts, configuration settings, etc. And this doesn't need to replace basic display of LeafScan. Touchscreen of phone would eliminate several buttons on device also. So, this way one can think of this as more sophisticated version of Nissan Carwings app.
If Raspberry Pi was part of the hardware, phone can connect to it easily with bluetooth or wifi.
Also, using Raspberry Pi for network connection might possibly eliminate your FCC clearance requirement. In a previous post you mentioned that you didn't want to put bluetooth in Leafscan as it would impose requirement of FCC approval on you.
If both smartphone app and LeafScan LCD are not possible, and if I have to vote, I would vote for only a smart phone app and mount my phone! If I have to vote between Android App and iPhone App, I would vote for Android App first and an iPhone app later but of course I am biased due to the phone I have!!
If it is a combination of Raspberry Pi and a smart phone, LCD may be unnecessary and that can significantly reduce cost. Also, this way, the hardware (Raspberry Pi) can remain hidden down below anywhere in the car and not be at risk of getting stolen.
I would be interested in your thoughts about this.