six doored car with 8 seated?

They used to call these "airport limos" but they have been pretty much replaced by mini vans or shuttle buses at airports. Some funeral homes use this kind of vehicle to carry pall bearers from the funeral home to the burial site. They are custom built by the same companies who build stretch limos.

Some limos have six doors but no regular production car does.

Funeral homes use six door limos. Look for a company that sells them.