Jamie McMurray was the unlikely winner of an uncharacteristically dull race at Talladega Superspeedway, where a ban on bump-drafting forced most competitors to treat the event as a slow Sunday drive.

But two spectacular crashes at the end claimed several cars, including the Toyota of Marcos Ambrose, denying the Australian the chance to get a fourth top 20 finish on a superspeedway this season.

The day started with a stern warning from NASCAR president Mike Helton against the aggressive driving that has turned Talladega into the most exciting track on the circuit.

What followed was an anaesthetised first 450 miles, with long periods of single-file traffic and no driver willing to defy NASCAR's order not to bump through the corners.

But the action picked up with roughly 20 laps remaining and with it came the typical Talladega mayhem.

Ambrose and two other drivers were taken out by Ryan Newman's harrowing end-for-end crash with five laps to go; Newman's car finished upside down in the grass and there was a stoppage of almost 13 minutes to cut him free.

That set up a two-lap sprint to the finish and that was halted when championship contender Mark Martin went flipping across the track in his own spectacular crash.

The race ended under caution, with McMurray in Victory Lane for the first time in 86 races.

Jimmie Johnson, meanwhile, likely wrapped up his NASCAR-record fourth-consecutive championship because of all the late action.

Johnson was stuck back in the mid-20s when Newman crashed and he quickly pitted for fuel - a decision that may have clinched the title.

When cars ahead of him began to run out of gas because of the red-flag delay, Johnson vaulted up the standings.

He finished in sixth place to stretch his lead in the standings to 184 points over Mark Martin with three races remaining.

Ambrose was classified in 34th place, dropping one place to sit 18th in the standings.

"From where we were with the red flag to where we finished, I'm still in shock," Johnson said. "I can't believe that it worked out. I can't believe that many guys ran out of fuel and put themselves in that position."

He had dreaded Sunday's race because of the unknowns that come with the horsepower-sapping restrictor plates that are used to control the high speeds at the 2.66-mile track.