I reckon it's probably not that bad, there are big surfaces that are almost normal to what would be incoming radio energy. Stealth shapes tend to reflect energy in a completely different direction from the source.
Here's the closest thing to data I've been able to find. I have no idea what to do with this info.
The polar plot at the end would be useful if there were plots for other cars and trucks to compare to. I'm assuming that it's a simulation?