"I couldn't quite win the final race of the day and that would have been a bonus [with an entry into Australia's famous Manjimup 15,000 Motocross event the prize], and I congratulate Hamish Dobbyn for winning that, but the main aim for me was winning the class outright," Groombridge said.
"It was all about consistency today and not hitting the ground. I didn't actually think I would be able to ride today after my big crash at last night's Speedcross. I was a bit sore today but I guess I came up with the goods in the end.
"My fitness is very good and I'll keep working on that as the nationals approach ... there are a few other big events for me to concentrate on too, starting with the Acerbis Four-Hour cross-country race this weekend, and then the Auckland Motocross Championships, the annual Whakatane Summercross and the New Zealand Motocross Grand Prix at Woodville."
Meanwhile, Honda rider Ben Townley won the inaugural Speedcross event - a hybrid event that mixes speedway with supercross - on Saturday night. Townley, who lives near Tauranga, swooped in to claim the top prize when the two lead riders in the final race of the night - Groombridge and Dobbyn - collided and crashed just two corners from the end.
Hamilton's Josiah Natzke won the MX2 class overall, finishing the day ahead of former grand prix motocross star Josh Coppins (Altherm JCR Yamaha) and Taupo's Cameron Dillon (Huka Honda).