NASCAR drivers spent the morning session of Tuesday preseason testing working on single-car runs in an attempt to feel out its new 2013 car.

But all the solo laps didn't answer one question: How will the "Gen Six" cars handle in traffic?

Will the dreaded "aero push" be reduced? Will it be easier for drivers to run side-by-side and make passes? After all, those are some of NASCAR's stated goals, all in an attempt to make the racing better.

There was only one way to find out. In the afternoon session, nearly a dozen drivers got together and made two 15-lap runs – 'heat races,' if you will – to see how the cars handle in traffic.

Nothing conclusive came out of the sessions, but it was interesting to see so many cars getting racy in a non-competitive situation – especially preseason testing.

Denny Hamlin made a pass on Brad Keselowski to finish "first" in the early heat race; it was difficult to tell who "won" the second session, because several cars dropped out.

Check out the video above to see more.