At last year's first Barcelona test, the Alfa Romeo team was hit by various reliability issues, a trend which continued to persist throughout the season.
But last week Bottas and Zhou Guanyu completed a combined 401 laps over three days, albeit after one stoppage for Bottas with a suspected Ferrari power unit issue and a minor systems error.
"It was definitely way better than last year at this point," Bottas commented on the C43's reliability. "So, I think we're well prepared, as well as you can with three days.
"I feel like we've stepped up as a team in terms of the quality of the car, we have had fewer issues by this point.
"Last year, testing wasn't so much fun, so we're in a good place after three days."
As well as reliability, Bottas says the Sauber-run team has addressed the 2022 car's high-speed instability, its other main weakness.
"I definitely feel the improvements we've been trying to do for this year, and the stability of the cars is much better. And that way, you can gain more confidence," he explained after ending the test third-fastest on Saturday.
"There's nothing fundamentally wrong with a car, so I think we managed to get the set-up quite nice in these three days.
"It's really nice to drive, so it's a good starting point, for sure. I think I only had like one little lock-up in one full day."
The Finn hopes an improved balance between high and low-speed behaviour will widen set-up options as the team won't have to make so many compromises.
"There's still a bit of a difference between high to low speed, but I would say it's at least 50% better than last year, so that opens up quite a bit of set-up options.
"It's much better than last year. The tendency seems to be that - if anything - on high speed the balance is a little bit neutral."
Last season, Alfa Romeo finished sixth on countback with 55 points, 49 of which were scored by Bottas.
But ahead of his sophomore season, Bottas' team-mate Zhou made a more confident impression in winter testing, admitting "he feels much less pressure" than during a tricky debut campaign.
