It's difficult to navigate, even with beacons tbh. And with car you need to be very soft , because it's very drifty.
But I think the issue is the world. Is way too big, and you noticed it as well. I'd rather maybe try to make a more linear game, because there it's easy to get lost and find the right way to get to the top of the mountain. I didn't managed to, because I didn't know where shall i drive unfortunately, even if I saw the beacon from far.
I'll try to add checkpoints instead(just one activate at once) and when you achieve this checkpoint, activate the next one. And maybe arrow, which shows, which direction you should move to that checkpoint.