Actually it does. It works with the same principles of an off center fed dipole. As long as both sides add up to equal and electrical 1/2 wavelength, the antenna will function.
What I was talking about was the electrical length presented by said vehicle chassis. I've actually taken a 1/4 wavelength whip tuned for one place on one vehicle and on a different vehicle I had to retune it. I've seen some that you have to tune a little longer than the mathmatical resonant 1/4 wavelength, and others that you have to tune shorter, hence why I specifically honed in on your words, namely "ball park". I have seen this personally multiple times.
If you want to say that their is capacitive coupling between the chassis of a vehicle and the earth (or in most cases street) below, that is fine, I would agree with that, the chassis of the vehicle does act much like a "capacitive ground" system, which used to be used on old AM broadcast towers. This type of ground system is well studied and experimented with, and how well it works is directly related to the conductivity of the earth below the said capacitive ground system. The conductivity of street pavement is terrible to even worse. While their are currents that will flow on the earth below and around the vehicle (aka the street), they will be very minimal, especially compared to the currents flowing in the chassis of the vehicle itself.
Seriously, look at a ground mounted 1/4 wavelength vertical antenna. Why does it work better if you use actual radials on (or buried just below the) earth as opposed to a ground rod for an earth connection? The reason for this is the exact same as the reason I am saying the above currents flowing in the "street" will have no noticeable effect compared to the currents flowing in the chassis of the vehicle.
As I said above, from experience, their isn't one length of whip that will tune to resonance on every vehicle. As the electrical length presented by a vehicle will changes from one vehicle to another, if you are tuning specifically for resonance you will have to make an adjustment to compensate, and the easiest place to do that is the length of the whip in question.
I wasn't disagreeing with what you said, in fact, I was simply restating what you said from a different point of view. What I said was, in fact, dependent on what you said being true.
The DB
