The thought of building a car with an IR transmitter has been kicked around in engineering for some time. The Cab-2 would be able to program the module that transmits the IR info once entered into the Cab-2.
Basically, configure the Cab-2 with the data you want transmitted, set the car to the same ID as the loco, press a Cab-2 button, and IR data will be configured by the Cab-2 and then be transmitted by the car,