AMA once more turned on the power to produce an absolute rip-roaring season of flat-out MX action. 

Could Dungey defend his 450cc crown and repeat his run of victories from 2012? 

The hard-charging Villopoto had other ideas and stamped his authority from the first round at Hangtown. 

In the 250s Baggett, Osborne & Musquin just couldn’t stay with Tomac and Roczen who pulled clear at the top. 

Highlights from both classes at every round make up a comprehensive review of another classic year in one of the World’s most popular MX series.