"The 2019 season will be a new challenge for all of us", said the team principal.
Before the W10 headed out on track at Silverstone, Mercedes released a series of digital images of the vehicle they hope will carry them to a sixth successive victory in the constructors' championship. "We need to prove ourselves again - against our own expectations and against our competitors".
"Five double championships is far more than we would have ever expected but every season starts with zero points".
While Williams and Renault are struggling to get their cars together in time for a pre-test run, Mercedes made it out for a shakedown at Silverstone five days before the main Barcelona test begins.
"Some components surrender what feels like a giant step of half a kilo, others just a few grams, but collectively each of these victories add up to a handful of kilos that have been invested back in the vehicle on aerodynamics, suspension and power unit to bring performance".
"Since 2017, it's the second time that we've had a huge shake-up in the regulations", said Wolff.
"We have to start from scratch".
The Mercedes chief also gave his backing to Bottas after a hard 2018 campaign in which the Finn struggled to keep pace with his team-mate. "Valtteri knows he has the full backing of the team to succeed and he's excited to get back in the vehicle and show his critics what he can do", said Wolff. "Driving the new auto is like meeting someone new for the first time - you want to get to know them the best way as quick as possible as you embark on a journey together".
Mercedes have appointed Esteban Ocon as their reserve driver for 2019. Briton Hamilton, who won his fifth world title past year, will lead Mercedes again alongside Valtteri Bottas for the third season. Let us know in the comments!
"The handling of the W09 was a big improvement over the rather idiosyncratic W08".
"They are a threat because if you are not as smart and you didn't see how to make the most of these new regulations, then you'll certainly suffer in the coming season. We have worked hard on the suspension and aerodynamic characteristics to deliver a auto that will be much kinder to its tyres - enough, we hope, to allow us to be competitive at all phases of the race and at each track on the calendar".
Hamilton, who will be partnered at Mercedes for a third successive season by Valtteri Bottas, will get his first taste of the new Silver Arrows during a private filming event at Silverstone on Wednesday afternoon.
Sky F1 will also be broadcasting live coverage on Tuesday February 19, Wednesday February 20 and Thursday February 21 between 1pm and 6pm.
A dawn-to-dusk live blog will also be available on the Sky Sports digital products for every day of winter testing, along with features, insight and reviews from Barcelona.
Get the dedicated Sky Sports F1 channel - the exclusive home of all live F1 - for £18 a month in HD with no contract.