use an impact drive on them

make sure you use the correct screwdriver bit on them as well, it's very easy to kill the heads on them if you use the wrong tip

worst case scenario is that you will have to use a punch to knock them around a bit before they'll come out or drill the heads off

the ones under the ashtray are proper fuckers, so use the longest screwdriver you can to get a good hold on the head of the screw

not sure you can get replacements now and there were at least 2 different lengths and at least 2 different head sizes depending on the location they were used