Jack Miller didn't give much away about the new Ducati parts he had been trying – fairing, engine, exhaust and possibly a new ride-height device - during the final MotoGP test of the year at Jerez.

"Some positive, some negative. Like anything you test. Now we need to reassess how everything has gone and make a plan from there," said the Australian, who set the tenth fastest combined lap time, 0.8s behind team-mate and test leader Francesco Bagnaia.

Before being fastest at a tight and twisty track like Jerez, Ducati - tradtionally known as a top speed bike - had won four of the final six MotoGP races with Bagnaia (who also fell from the lead in Misano), including a top-three front row and podium sweep at the last round in Valencia.

Ducati also won races with three different riders this season, with five different riders standing on the rostrum.

With 2022 chassis parts yet to be tested, Bagnaia left Jerez saying Ducati had already improved on a GP21 he considered 'perfect'. Miller backed up that view by agreeing that, if improvements to the current package are made, the GP22 has the potential to dominate next season.

"I think so. I think by ironing the kinks already out of the GP20 last year with the GP21 - which was nearly the same bike - we were able to be very dominant towards the back end of this season," Miller said.

"Not myself in particular but Pecco and other guys. And [I was] able to be there or thereabouts most weekends. For sure if we can make any improvements, I think we have a good chance at it [in 2022]."

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The new longer lower Ducati exhaust, being tested by Francesco Bagnaia at Jerez.

While Ducati chassis parts are expected for the next Sepang test in February, Miller was among those to try a long exhaust at Jerez.

"You mean the didgeridoo?" Miller smiled. "We call it the didgeridoo in the box.

"We tested it first in Misano and it's good. I'm not going to tell you exactly what it does, but it's better in some places, worse in others…"

Ducati will expand its MotoGP presence from six to eight machines in 2022. Five riders will use the latest GP22, the others the GP21.

Miller's own racing season will end in the first week of December with a surprise appearance in the Australian Superbike championship.