Try editing spawn_info_groups.xtbl in common.vpp_pc. There are a fair amount of MP and demo-exclusive spawn groups, so I assume this is the file but I could be wrong especially since the DLC might have given a different version of this file. (this file is the one that needs editing for SR3 and above)
For all vehicle variants you can refer here:
There are
131 Vehicles in Vanilla Saints Row 2:
• 9 Bikes
• 7 Boats
• 41 Cars
• 6 Helicopters
• 1 Minivan
• 4 Planes
• 32 Special
• 7 SUV
• 17 Trucks
• 5 Vans
• 2 Wagons
+2
GotR Exclusive Vehicles
+15 DLC vehicles (Available for PC
here.)
Some Vehicles have multiple in-game names. These are listed below in parentheses...
And their variants:
Note that if you are opening with voliton's table file editor (attached for convenience if you don't already have it), you will also need teams.xtbl, character_presets.xtbl, vehicles.xtbl, and traffic_types.xtbl which should be in the same extracted folder.