You can't extend the amount of time till it respawns (that I've figured out yet), but it willl stick around longer if it isn't completely destroyed. If you damage it enough to just set it on fire it'll be around for about 1 to 1.5 min (haven't timed it yet). The reason I can think of that makes this helpful is if you are building a phased game. I've been inspired by the "No Hope Act 2" map by Rifte, I'm planning on dedicating my time to building "campaign" style maps with timed events. There are alot of talented guys making competitive/MLG style maps, so I'll leave that to the "experts". If you time the segments of your map you can have these burning vehicles late on in the round. Ex. Vehicles 1, 2, 3 set on fire at start. 60 seconds in, vehicles 4,5,6 blow up in the next section. 2 sec later a ramp appears giving you access to the next section. 120 seconds in, vehicles 7,8,9 blow up in the next section. 2 sec later a ladder appears giving access to the next section. and rinse repeat. UNFORTUNATELY... You can't delay spawning for longer than 180 seconds (that I've heard)... But I have some thoughts on that too. I'll post a tut if I get my idea working. I will be working to find a way to keep them longer but there's no guarantee I'll find any trick to do it. I think if you got in the vehicle then get out it'll stay longer, so maybe there's something else that could affect it in a similar way.