Same here, if you can aim mainly through the windscreen and keep the controller up on the dash it works surprisingly well though better without anything running I suspect.I've been doing it. I won't set any distance records, but within a mile it works ok. It doesn't cut out much more than if I was standing outside. Nice and comfy, and good shade for the tablet. It would be pretty sweet to have a magnetic antenna that could be put on the roof.
Main advantage is being able to see the screen but also can keep warmer/cooler.
Additionally you are less likely to have randoms walking up and asking distracting questions.