There are a dozens ways to drive internet leads, here's just one suggestion.

If you have AutoTrader.com, AutoTrader allows you to attach 3 up to 3 minute videos for each vehicle.  Now take any cheap video camera and get an editing program as an example Studio. 

This will be your only investment, now do some "companion selling", as an example, let's look at cars from $3999 to $8999 bring them on to the showroom one at a time and do a 30 second walk around and pricing, then edit all 6 videos together and attach them to every car on you autotrader back end. Attaching to all of your inventory can be done with one click.  Now take like cars, luxury or sport or trucks or SUV's and do the same thing.

Now when a customer searches for as an example a cheap car they get to see your video and 5 others that compare in price, or if they are looking for a SUV and click on one of your SUV's the get to see 5 other you have in stock. This not only keeps the customer looking at more of your vehicles, but keeps them from searching other dealers.

Adding video to autotrader is easy and increases the duration of time a customer spends looking at your inventory by 60% or more.