Perhaps if you have a stubby little antenna like what you mentioned... (especially if it's mounted so low it's almost entirely blocked by the vehicle's body)Standard 4 Watt CB radios are good for about 5 miles tops in normal conditions. Get back in the woods and you're lucky to get 2 miles out of it.
A decent setup should normally reach about 10 miles or so (provided the party you're talking to also has a decent setup too). 50 or more miles is easily possible if you have a clear shot across a valley or between hilltops.
5½ foot Francis whip w/spring on a triple-mag-mount. The spring keeps trouble with tree branches at bay.