The Bat-train appears in Batman Vol.1 #95
It's a standard locomotive of its era and had five passenger cars as well as two flat-cars for storing the batplane and batmobile. There would be comfortable space for 450 passengers seated and standing or you could crush-load over two thousand passengers if you removed the seating.
We're introduced to the Bat-Truck in the recent Batman Vol.2 #42
This truck is mostly storage space and appears to be about the size of a double-width, extra-long shipping container which means it could carry at least a hundred and fifty people in relative comfort (approx 2ft of space between each person) or nearly 400 if crush-loaded.
The Flying Bat-Cave first appears in Detective Comics #186.
It appears to have ample space for at least 30-50 passengers and maybe more, depending on its maximum take-off weight.
The two original Batmobiles were a 1939 Cadillac Fleetwood 75 (complete with drop-down seating for four passengers) seen in the 1942 serial movie Batman
and a 1949 Mercury 2 Door Coupe (used in the 15-part serial New Adventures of Batman and Robin, the Boy Wonder capable of seating six in comfort.