Single car trains. Riders are arranged 2 across in a single row for a total of 2 riders per car.
There is a bit of conflicting information on when the Swamp Buggy existed at Astroworld. The Swamp Buggy existed on both 1971 and 1972 park maps. But oddly there seem to be two different park maps copyrighted in 1972 and on one, the Swamp Buggy is not present. It is suspected this map is really a 1973 map produced in late 1972 or perhaps not changing the copyright was an oversight.