I've tried a lot of antennas for 75 meters mobile, but the best thing I've found for LOCAL (out to a 300-mile radius) is:
1. Two "dummy load on a stick" 75 meter hamsticks
2. 1 Dipole adapter bracket (allows you to hook two hamsticks up horizontally like a diploe and connect the whole thing to a mast pipe)
3. Attach said mast pip to heavy duty "trailor hitch" or tool box mount.
4. Keept the thing at least a couple of feet over the top of your vehicle (it will be about 14 feet/7ft per side long)
5. Have fun - mine works within 3 S-units to local stations of what my full-wave loop at 38 feet does at the home qth. Not too bad for only 100 watts mobile...
6. Yes, the hamsticks are very inefficient, but when you shoot most of the signal straight up NVIS style, it doesn't take many watts to achieve good local communications. The top of your vehicle makes an EXCELLENT reflector ;-) (the Germans invented this type mobile antenna set up back in WW2, and they only used about 3 watts AM on 6 MHz to talk all over the Russian front for example...)
7. Yep, it is ugly and weird looking, but it works...
8. You can use quick-disconnects on the antennas, and then switch in 60 and 40 meter antennas for more NVIS fun if you want to do so
9. Best of all, you don't really have to bother with all of that ground-strap bonding drudgery as your antenna is ground independent because it is a shortened dipole.
Good luck with whatever you decide to use; I hope to hear you on the bands sometime!
