I hate banging a 1/4 whip on the bottom of the garage door every time, but that may be the best answer. Besides, what could be more intimidating on the highway than a black Chevy Tahoe or Ford Expedition with a whip antenna and a lo-pro 800 MHz antenna on the roof? "Do you really want to pass me? Really?"
My pickup doesn't fit in the garage, so not an issue for me. My wife's car is a Ford Escape, and it's got a 1/4 wave VHF on the top. It hits the garage door. No where near as tall as a suburban, but still, it hits. After doing this for 5 years, I've seen no issues at all with the antenna or the mount. Maybe a slight mark on the inside of the garage door where it hits, but that's it.
I did briefly consider one of these low profile antennas for hers, but everyone (and I mean -everyone-) I talked to who had tried them had referred to it as a "waste of money", and each and every one of them had taken the antenna off and replaced it with a quarter wave. I was offered a few of these old antennas because no one felt they were worth anything more than the trash can.
Most people won't even notice a 1/4 wave whip on top of a vehicle at highway speeds. Personally, I think the 1/4 wave antennas are "lower profile" than the soup can sitting on top of the vehicle.
If image is really a concern, get one of the Stico boxes that allow you to use the AM/FM radio antenna. We've got one of those on the chief's car and it works well enough.
Other option would be something like a Panorama Antenna "shark fin" with the VHF whip. Looks like a modern AM/FM Satellite radio antenna. They'll provide a port for cell, 2.4GHz, GPS and a stud that permits installing a whip of your choice. Not cheap, but it would likely blend it better than anything else (other than the Stico).
