You might not be American. I had the same confusion when I called 911 to report an accident driving across the US and they asked me if the truck was a "semi".
I’ve been trying to work out the relevance of you driving a Porsche and the weird phasing (you called your car?).
Ironic confusion given the discussion on regional lanagaue variations.
https://en.wikipedia.org/wiki/Semi-trailer_truck