There may be an unusual answer - you'll need a power inverter in your car or an alternate way to power this...
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Unify4Life™
It's made to be a home remote control for home theater and home automation gear. Software on the handset sends commands to a small bridging box over Bluetooth and the box sends out the remote control codes over infrared. The whole package is $99.
It should be fairly easy to adapt to this application - if you have the Supra E-Key IR protocol specs, get them to Unify4Life and see if they can add that capability.
This doesn't officially ship until the end of October; it's possible they can also come up with a car or battery power alternative for this kind of application if there's enoughb demand out there.
Alternately, have you thought about adapting a non-phone programmable universal remote control for these codes?