But, by then the damage had already been done, with Cooper having won the first two races of the day to give himself a seven-point buffer even before the gate had dropped on that final race.
A third placing or better in the final race would have been enough to hand the title to Cooper anyway, and his victory in that race, while Ferris failed to finish, was merely icing on the cake for the Kiwi hero.
"I guess I offered Dean (Ferris) a chance to win the title when I gave up my 13-point advantage at (round three in) Palmerston North. But I won all three races today and that was that," said Cooper.
Third overall for the series was fellow Mount Maunganui rider Rhys Carter (Kawasaki), a surprising result since he had started the day at Taupo only fifth in the championship chase.
But Carter also showed his liking for the sandy Taupo circuit, finishing third overall on the day and rocketing past Australian professionals Todd Waters (Honda) and Luke Styke (KTM) to claim the final step on the series podium.
In the MX2 (250cc) title chase, it was just a matter of defending champion Hamish Harwood staying cool to keep the crown.
The Takaka-raised but Takapuna-based Harwood took his KTM bike to post a 2-1-1 score-card on Saturday, easily enough for him to keep Christchurch's Dylan Walsh (Yamaha) at bay.
Walsh finished 1-2-3 on Saturday and ended the series 16 points behind Harwood, with Waitakere's Ethan Martens (Yamaha) taking third overall, a massive 57 points further back.
The 125cc class was also virtually only a two-rider battle, with Taihape's Hayden Smith finishing behind his main rival on Saturday, Karaka's Kurtis Lilly, but that was still enough to win the title.
Mangakino's Maximus Purvis (Yamaha) won the day in the 125cc class at Taupo on Saturday, but this was his only appearance in the series, because of injury, and so he had no chance of winning the title.
Leading final overall standings after the fourth and final round of four in this season's New Zealand Motocross Championships at Taupo on Saturday:
MX1 class: 1. Cody Cooper (Mount Maunganui, Honda) 270 points; 2. Dean Ferris (Australia, Yamaha) 238; 3. Rhys Carter (Mount Maunganui, Kawasaki) 210; 4. Luke Styke (Australia, KTM) 209; 5. Todd Waters (Australia, Honda) 179.
MX2 class: 1. Hamish Harwood (Takapuna, KTM) 280 points; 2. Dylan Walsh (Christchurch, Yamaha) 264; 3. Ethan Martens (Waitakere, Yamaha) 207; 4. Hadleigh Knight (Reporoa, Husqvarna) 193; 5. Logan Blackburn (Te Puke, KTM) 177.
125cc class: 1. Hayden Smith (Taihape, KTM) 277 points; 2. Kurtis Lilly (Karaka, Husqvarna) 272; 3. Hayden Wilkinson (Nelson, Yamaha) 201; 4. Dan Bell (Levin, KTM) 181; 5. Jordan Milsom (Te Puke, Husqvarna) 146.