There are two very easy ways. First, park your vehicle in a place where it will not become hot, then drop in:
A: A blind snake. Great for ants, but I don't live in a good area for them.
B: A few small lizards. I always keep a few around, to keep an eye out for spiders. Lots of those nasty wolf spiders around here in eastern NC.
C: A preying mantis or two. Ants might not be their favorite, but anything is food if you are hungry enough.
D: ....ugh... A few spiders... Hunting spiders will tear those ants up, but you will need more than one... I hate spiders.
E: That anteater Jen mentioned.
More reasonably, simply lay some cardboard down and stretch out those cheap spiral fly traps that you pull out of those little tubes. Nothing gets away from those. Don't hang them or let them touch
anything in the vehicle, though. You will never get that crap off. Any similar trap will suffice, even those improvised from various tapes or adhesives.
Poison isn't always effective with ants, and even if it is, you end up with dead ants everywhere, which attract things that eat dead ants. That's not cool at all. Land Rovers
already seem to attract more spiders than other vehicles, and there is no reason to encourage more.
So, get something that eats them, or get something they will stick to. Don't muck about trying to poison the damned things.
Cheers,
Kennith