It might be worth a few $ to try. I hooked mine up to power while inside my house, beside my computer and monitor, near a CFL light. Cold boot (first ever power on) took a couple of minutes. Even with all the EM interference and reduced signal strength from passing through asphalt shingles and layers or wood, according to google earth, I was less than 1m from where I actually was!
Maybe incorporate this into the headrest instead of below the seat?