Win the points championship in career mode to unlock the following cars and clips.

One time: Greg Biffle's and Shane Hall's Busch car. Note: This also unlocks another clip in the EA Sports section.
Two times: Kevin Grubb's and Randy LaJoie's Busch car.
Three times: Jason Keller's and Jamie McMurray's Busch car.
Four times: Chad Little's and Michael Waltrip's Busch cars.
Five times: Elton Sawyer's and Mike McLaughlin's Busch cars.
Six times: Jay Sauter's and Mike Dillon's Busch cars.
Seven times: James Finch's and Scott Wimmer's cars.
Eight times: Jeff Green's car.