Well, I hope it’s clear that simply being aroused is not a sin, unless you were actively seeking it. And it appears that is not the case here. I mean, if you think there’s a real possibility of you acting on that arousal in whatever way as soon as you get out of the car, or something, then perhaps you should not take the ride.
Anyway, if you do take this ride, and find yourself aroused, just ignore it! I guess that’s being simplistic and perhaps is easier said than done, especially for different people. But, how long is the ride? Are you just sitting there in silence, or what? Generate some conversation to get your mind off whatever it is. The key in this situation is 1) not acting on the arousal (and not seeking it), and 2) and distracting yourself from it/ignoring it, and/or rejecting it as soon as it comes.
That’s the thing with temptations - often, if we firmly reject a temptation as soon as it comes, its hold on us tends to either lessen or fully go away. Keep that in mind and you may very well be just fine. Obviously, you know yourself better than any of us on here, though. Consider these things and make your decision.