It depends on the vehicle. It can be done, however the individual vehicle may have a lighter circuit that is NOT independant and have other ancillary loads on it, or may be fused less than the load of the radio. I know that certain vehicles (E series fords) have lighter circuits that are fused for 20 amps, and are independently wired. However, some of the other vehicles on the road frequently share AM-FM radio, or other loads with the cigarette lighter. If the vehicle you are trying to put it in will support a load of a properly fused radio, it CAN be done.
Some concerns about it are as follows;
1) The radios are designed to be wired to a constant 12vDc (fine 13.8

) and will not keep "current channel" settings when they are unplugged (I don't recall what else they would keep, but i don't think it's anything) Now a simple radio like the GM300 can probably be used just fine in this capacity, however...more complex radios (or finickey radios YMMV) require constant voltage due to the fact that they are never really OFF, just powered down or in a standby state (IE CDM series - since they have soft off function).
2) cheapo connectors will heat up, heat will cause inefficiency in the circuit, drawing more power, heating up more, drawing more power, heating up more and ultimately exceeding the fuse capabilities and blowing it. I consider any cigarette lighter a cheapo connector, so i would make sure if you are going to do this...get the highest current adapters you can find and fuse them appropriately. **If it's the same group of vehicles that you are just rotating between, I would just wire in a military connector and plug the wire on the radio for the other end, so you get a waterproof connector w/ good strain relief & locking mechanism - however, this may not be possible if it's a different vehicle every time, you're outta luck**
3) Moto recommends that this unit be wired directly to a battery source, to prevent "alternator noise" from getting into the TX RX path. Using a cigarette lighter is a "little far" from a battery for their specs, but again YMMV.
It is possible, just be careful.