My Sirio Performer PL5000 and 145 mag mount works wonders on my mini SUV. Definitely changed the car's look but form(good)follows function.
The only car I know has problems in my family is a 98 Saturn. Very little mettal is on the body mostly Fiberglas and plastic. The only parts of my car that are anything but good conducting mettal are the bumpers and lights. The Saturn will get a good range of about 25 miles for about two months then sudenly it drops down to about 5. Take the cb to a shop and they say it's ok so I figure it's the ground plane. The antenna often has to be changed out so my grandfather finally gave up and took the cb out. I figure the honda only needs 5 miles but hey the more mileage the better I suppose. O and I finally found a good spot for it. The old tape deck location turns out is perfect if you cut it out and make a nice looking faceplate for it. Can't believe I did not think of that sooner.
Sorry but that is wrong. The amount of groundplane for 11m is just fine and here in Europe we have no problem doing 30 miles with 4 or 5 watts with antennas mounted on our "tiny" cars.
If the range was that low it is because you did a crap job of the installation. A friend of mine did a poor installation job on his 18 wheeler and had a range of 2 to 3 miles with 100W...