If you decide to go with Railcom or similar direct -- not mag -- mount antenna, please do as I suggest and not as I did. The roof mount on my car works very well, except for parking garages. Taking the mast off wasn't a problem, at least initially. Enough northeast road salt and other complications led to galled set screws, which led to rounding over the set screws, which led to getting a replacement after 18 months. The new plan -- which in retrospect should have been the original plan -- is using and occasionally reapplying anti-seize compound to the set-screw threads. If there isn't another post on this subject from me in the next 18 months, you know the anti-seize compound is doing its job.
"A gray crossover is definitely not company transportation."