The Finn, team-mate to five-times world champion Lewis Hamilton at Mercedes, gave his assessment on the final day of the first four-day pre-season test at Barcelona’s Circuit de Catalunya.
Ferrari was fastest on the first two days and the Italians also covered an impressive amount of mileage in the new SF90 car while Mercedes has been working through its programme without setting any eye-catching times.
Bottas said the cars would be very different by the time of the Melbourne race on March 17 and Mercedes had new parts coming before then. He warned, however, that even with the upgrades Mercedes still needed to make the car better and quicker, with work to do on the balance.
“It feels a little bit different (to last year), at least in these (winter) conditions,” he said.