Hello, unfortunately this is the first time I encounter such a problem. Thanks for the report, I'll see how it can be fixed. For now you can try to reinstall the game or reset the saves (just rename folder My Documents/My Games/Slowdrive). Sorry for the inconvenience.

foofaraw: Have you tried restarting the game then redoing the same map? In my case it allows me to grab the leaf (from any direction).

onebraverobot: For me it happens only after I have already grabbed one leaf in my play session, after that I just pass through them as if they weren't there until I restart the game.

In some cases I managed to grab more than one in a row, but it seems that it was only on maps that I had not completed yet, although I'm not sure if I had no star for the map, or at least one and less than three.

I'm running the Linux version.

-edit-
I did some further testing and it effectively seems to happen in some maps and not in others, just like OP stated, no matter how many stars have been collected. But one thing stays true nonetheless, the first leaf is always picked up correctly for me, after that it depends on the map.

Hope it helps in your investigation.

I appreciate your help very much, but truth be told, once I got into MIST, the game kinda got beyond my abilities. (I did got a #7 HS on an ICYROADS track, and I think I'll bow out with that success.)

After re-installing at the developer's suggestion I did manage to get one of the leaves that had evaded me, but no others. I was still able to drive right through them, to no avail.

Thanks again, and best of success to you.