Bears' olfactory sense is
thousands of times stronger or more sensitive than humans. (another bear article:
The Nose knows)
I am pretty sure they can tell the difference between old spills and fresh food in your car. Just clean it out/vacuum it well. That
should be sufficient.
...Although ten or more years ago, we had a bear get into our van when there was no food. However, I had left a Subway sandwich in the car and started up the Whitney trail. Went back and retrieved it after a short time. But the bear could smell the evidence, so had to get in and inspect things. It pushed the glass down, stripping the motorized window gears, but didn't break any glass. Powerful claws!
