I have a few CB radios, none currently installed in a vehicle. Although when I am traveling a distance I do like to have one with me. As far communicating on a caravan, FRS is an ok option but very limited range. Usually in a caravan we use GMRS, although it does need a license you can use higher power and better antennas than FRS. Both are on UHF and have their limits.
CB radio does work if it is set up properly as was previously mentioned. But again there are limits of about 5-10 miles. One thing to keep in mind though is on CB, right now we are at solar minimum and that closes propagation (skip conditions) for the upper end of the HF spectrum, where CB resides 27mhz. But when solar conditions improve, then you start shooting skip as they say and can talk very long distance which can be fun, but if trying to talk to someone close may be impossible, not to mention trying to find an open channel.
Another option is Amateur radio, you have to be licensed, but there are repeaters around almost everywhere. Now you may not find a lot of traffic conditions here, but if its a long drive may find someone to talk to. But for now for traffic conditions and what not esp. on back roads someplaces, and interstates, CB can be a great tool.