Out performs any inside the car antenna. In addition to getting the antenna outside and higher where it can pick up more RF energy, getting the antenna out of your car removes it from all of the computer generated noise that modern dashboards and other car electronics crank out.Just make sure you completely follow the installation instructions:1 - Keep about 1 1/2 inches from the edge of the glass.2 - Do not place over defrost elements.3 - Will not work on tinted materials or metal in the glass.4 - Do not block driver view with the antenna.5 - The coupling box connector needs to be pointed up or down.6 - The antenna base needs to be pointed up vertical.Of particular note is #5. The instructions say the connector on the coupling box must point up or down, so please avoid the temptation to point the connector to the side. Mounting the coupling box sideways, with the antenna pointing up, must not provide for proper "through the glass" capacitive coupling.I've had a few antennas similar to this TRAM on different cars over the years and they all perform well for wideband scanners. I've never had one come off, flop over, or give me any other problems. They permit you to avoid drilling a hole for an antenna and running coax through your headliner and prevent the inevitable scratches that will result from using a mag mount.