Stefan Bradl says he can feel a "clear difference" with Aprilia's 2016 MotoGP bike after wrapping up a three-day shakedown with the new machine in Qatar.
The Italian marque returned to MotoGP as a factory team last year with Gresini Racing, which previously had raced in a long-term partnership with Honda since 1997.
Alvaro Bautista, Aprilia's sole full-time rider of 2015, ended the season in 16th with two top 10 finishes, and he was joined by Bradl in the middle of the season.
The duo used last year's bike in the first pre-season test at Sepang, before skipping the more recent Phillip Island test altogether in favour of trying out the new bike in a separate test at Qatar.
"This test was really important as it was the first contact with the new bike," said Bradl. "First impressions are good. I see a clear difference compared to the old bike and we are moving in the right direction.
"At the moment I have a good feeling despite the fact that we have a long way to go before we'll be able to say that we're satisfied. That was to be expected at the beginning.
"This is a completely new and decidedly demanding project, but we can truly say that we are off on the right foot.”
Bautista added: "In these three days we explored the new bike, doing a lot of work with short sessions since this was the first real test with the 2016 RS-GP.
"Obviously we are not at 100 percent but we have a very good starting point. I think that we are already at a similar level as the end of 2015 with the difference being that we are just at the beginning.
"There is a lot of room for development whereas with the old bike we were at the limit. We still need to work on a lot of things but I'm pleased with the work Aprilia has done."
The duo will rejoin the rest of the MotoGP field for the final pre-season test in Qatar, which begins on 2 March.