The 2006 MotoGP world champion fitted a Michelin qualifier tyre to the '07 V4 during the final morning and went on to clock an amazing 2mins 0.592secs - nearly 1.4secs faster than Repsol Honda team-mate Dani Pedrosa's pole position time at last month's Malaysian Grand Prix.
"Overall we've had a good final day and it was nice to set the fastest time," stated Nicky. "We wanted to check a couple of details with the 2007 machine just before we said goodbye to it. The bike really worked well with the Michelin rear qualifying tyre, plus the track has definitely been cleaner at this test than at the race in October and the temperature for that fast lap this morning was a lot better than on the Saturday of the grand prix when we qualified - which was about the hottest day of the year here."
The 26-year-old then swapped to the all-new 2008 machine, currently slower than the 2007 bike, and completed a further 63 laps.
"We worked through a lot of stuff on the new 2008 machine, mainly engine mapping, electronics and tyres before we get to work on the chassis proper in the up-coming tests," said the American. "We always knew there was hard work ahead starting out with a completely new machine and I'm pleased we've been able to get on with it in the last few days.
"I improved constantly, which I'm pleased about, and we know what we have to do now. The weather was kind to us today and I had a snake-free day which was a bonus! It's time to go home now and I'm definitely looking forward to the break. I've only been at home for four days in the past six weeks and I've got my brother Tommy's wedding coming up, along with Thanksgiving, so it will be nice to get back," he concluded.
Colin Edwards was closest to Hayden on Saturday, the Texan setting a best lap time some 1.219secs slower than the Honda rider. However, Edwards set his time at the end of a four-lap run, indicating he was using race specification rubber.
John Hopkins complete an all-USA top three for Kawasaki, 0.236secs behind Edwards, despite bringing out the red flags when he fell shortly after 4pm.
Hopkins' new team-mate Anthony West and old Suzuki partner Chris Vermeulen also fell on Saturday - along with Honda LCR's Randy de Puniet. Hopkins and Vermeulen escaped with only minor scrapes, while West suffered slightly more substantial right arm damage and de Puniet injured a thumb.
Top rookie at the test was Andrea Dovizioso, who was just a tenth of a second behind Hopkins, while Vermeulen took the 2008 Suzuki to fifth - one place in front of new team-mate Loris Capirossi - and completed a consistently-fast 15 lap run on the final afternoon.
Double World Superbike champion James Toseland finished his first MotoGP test in tenth position, having dropped his best lap time by 0.7secs during his third day on an M1. Toseland left Sepang 1.7secs slower than Yamaha Tech 3 team-mate Edwards - a difference he and the team considered highly respectable given that he had never ridden the track, bike or tyres before.
The next winter test will take place at Jerez, Spain, from November 27.