It might even be an effective strategy to add a few extra cars to your parking lot, so it always has at least a moderate number.

When I worked at a mall food court, I noticed something interesting: during slower periods, sometimes one restaurant would have a line while other restaurants would have no customers at all. And not always the same restaurant. I attributed it to customers seeing that one place had customers, then inferring that it must be open and it must be one of the better places to eat.

Popularity isn't a very reliable indicator of quality, but it's not totally invalid either. If a place is always deserted, it's probably not very good. If it's always busy, it's likely that people are willing to wait for a reason.