I use the Opec Multi-band mobile antenna. It requires manually moving a wire to pre-set tap points, but it is inexpensive (<$100) and actually has performed very well giving me over 60 countries since I have been using it. (I am not an avid dxer.)
80 meters mobile sucks with any antenna less than a really good screwdriver. The best was mentioned earlier, the Bug Catcher!
However, I do know a few tricks. The Opec antenna is tuned for one little spectum of 100kcs. However, if you use the jumper in only the top holes, you can move the spectrum up 100-200 kcs!
Also, when operating mobile on 75 between Augusta and Atlanta, GA, I would follow a big-rig box truck. My signal would be reflected off the truck and shoot back to either Augusta or Atlanta (depending on which one I was going away from) and my signal would increase significantly. At that time I was using the Hustler and 75 meter coil.
The Opec antenna's weakness is where the coil is over the base. If you turn the coil to screw on the base, you will most lilkely destroy the antenna. However, I have been careful to use a pair of pliers opened wide to carefully tighten the antenna from the base.
Also, you have to make sure your SO-239 connector does not dig all the way into the bottom of the antenna. It will short the center and shield of the coax if you do.
My two Opec antennas do not include the WARC bands, but newer ones do. I have used them for over 4 years with little problem from them. One did lose the set screws and I had to replace them with screws from Lowes, but I use that antenna for portable use so being able to adjust the antenna lengths is easier with screws than set-screws so i consider it an upgrade
My Opec is mounted in the rear on the driver's side but it still hits lots of trees and over-head covers at fast-food restaurants. I deliver pizzas all day so it gets lots of abuse.
Today, I cleaned up the connections with contact cleaner and tightened the set-screws as general maintenance. I have only done that one other time previously. I admit it was in dire need of it, but it has been working very well ever since I got it.
The farthest I believe I have talked with it was Australia this summer on 15 meters. I usually operate on 40 or 20 meters, and rarely I use it on 75 but I have checked into a few nets with it running only 100 watts. I don't run 75 much at home either, it is just me.
I hope someone finds this interesting and useful.
Buck