Valtteri Bottas gave the car its first track mileage on a filming day at the Spanish GP venue, with Guanyu Zhou due to sample it in the afternoon.
It was the first appearance of the real car, previously seen only in show car form and in renders, and also the first track running for any 2023 F1 machine.
The Swiss team has paid particular attention to the rear end of the car, which has a new gearbox and a very different rear suspension and cooling layout compared to the C42.
However, the major focus for all teams even at shakedowns and in Bahrain testing will be the impact of the new floor regulations, which have been introduced to prevent the porpoising that was such a feature of the 2022 season.
The C43 is running a notably different floor in Spain compared to that seen in the renderings and on the show car, which had a very distinctive edge, featuring cut-outs.
Alfa technical director Jan Monchaux is hoping that the rule changes, and the extra knowledge that teams now have, will have addressed the problem. He also cautioned that the team needs to have a trouble-free test, especially in Bahrain.
"We have only three days of winter testing," he said. "And if we were caught in a similar situation to last year, it would be a nightmare. Because if we spent a day and a half in the garage, trying to fix the car, like happened last year during the first test in Barcelona, then the start of the season would be really in jeopardy.
"So the hopes are quite high, from what the FIA said, and all the metrics all the methods we've developed in-house, that the topic will be delayed, because you can't really get rid fully of a phenomenon.
"You can just postpone or delay the moment it gets triggered. And I hope with the changes of the rules and the work we've been doing also developing the new floor that it will be delayed up to a point where we effectively never gets there, and never have the porpoising.
"The very fact that I said probably means we will have some porpoising, I just hope it will be another team, and not us!"
Teams are only allowed to do 100kms on the two filming days they are allowed per season, using demo Pirelli tyres.
All teams are expected to undertake shakedowns in the coming days, with the UK-based operations running at Silverstone. Some teams, including Williams and Aston Martin, are set to use the second of their two filming days in Bahrain, just prior to the start of official testing.
