Guess it depends on where you live. Grew up in Oregon and I always say "pickup truck." We always say pop, I have never heard anyone ask for a "soda."
The first time I heard someone from the Midwest talk about 4 wheelers I thought they were talking about an ATV.
Now what about 18 wheelers?? I never liked that term. 18 wheeler usually implies a two axle trailer and is set up to go lower 48 and not over 80,000 pounds. When I drove I had 24 wheels. Should I still call that an 18 wheeler? A 24 wheeler sounds funny. Commercial vehical sounds too technical, and big rig sounds too colloquial. Maybe I should just call them semis.