With Simpe you can import obj files so that is the best way i think to export from 3dsmax.
There have been alot discussions about polycount.....
I have made many objects/conversions etc etc and depending wether it is a moving object or not i personal do not exceed the 30.000 polygons.
There are cars arround wich are 50.000 and they also will perform very well, just not 10 together on a heavy lot.

I have never had much issue's with high polygon meshes, moving meshes wich are textured heavily with patterns and such give me more problems.