a) Bill Lear also invented "learium" in an attept to revive steam.
b) First portable radio was developed by Howard Armstrong in 1923 and could be carried in a car. Problem was the need for a clean high-voltage (~100v) power supply for the tubes.
For many years car radios had a vibrator to step ip the 6v car battery. Most portable radios used an A-B battery with 6 or 9v on the A and 90v on the B side. They were expensive.
1.5v tubes came along in 1938 but the filaments were always fragile. Transistor radios started to appear in the mid-50s and that made the modern car radio possible. Instant-on solid state devices are relatively new.