[rct]

Autotrader.com and Cars.com are the two biggest players, and yes, most dealerships use at least one to list their inventory. However, many car shoppers do search individual dealer's web sites for inventory and find that it sucks.

In addition, I've found many cases where the latest inventory is not listed on Autotrader or Cars.com (and even on the dealer's own site). The only way to know for sure what the dealer has on the lot is to actually visit them in person or contact them via phone or email so they can check their internal system.