Glass Jars are the best way of keeping it fresh. Just make sure the buds arnt wet otherwise they'll mold and it'll be unsmokable.

The thing is, the interior will always get hot when the suns out, and thats not good. You want to keep the buds in a dark cool place, room temprature at the most, but never the kind of heat the car interior will get too.

Tell him to try and find a new place to keep it.