I use the Wilson 500 trimmed to about 56 inches where I found it tuned best at on a Mazda3 sedan, and a Wilson 1000 as it came from the factory at about 62 inches which it tuned at on an F250.
Both of these antennas have magnetic bases and are designed to work in the 11 meter band with assistance from loading coils located in the base of the antennas. These coils give them an effective electrical length of a quarter-wave for that band.
Although they are a bit less efficient than a straight quarter-wave 108-inch antenna, the Wilsons can be placed at or near the middle of the roof of my vehicles, thus giving them a clean and unhindered exposure to the airwaves in any direction.
In contrast, the big 108s usually are much too tall and gawky to place in this ideal location, so are usually relegated to locations much closer to the lossy ground and conductive metal vehicle bodies, such as on a bumper, and also biased to one side. Such a less-desirable location hinders the otherwise stellar performance of the big 108s, often to the point of making them no more effective than their shorter, coil-assisted cousins sitting up proudly on the roof.
All I know is that my Wilsons seem to talk and listen with the best of them out on the highways where it counts.