Speaking in a video released by the team, technical director James Allison says the world champions have found an impressive quarter of a second per lap by modifying the sidepods.
"The biggest [change we have made] is down here in the sidepod," said Allison. "We've done an awful lot of work down there to try to make that car really, really slender.
"If you compare it to [the 2017] car, you can just see the difference. You can see that the bodywork bulges out around about where the engine and exhaust pack is.
"On the new car this is a much, much more slender thing. It doesn't look like much of a difference but actually when you add it all up it is something like a quarter of second just there. It was actually a huge amount of work.
“A lot of hair got lost in that project, but the end result is something that is pretty to look at but also much more importantly is an awful lot quicker."
The pace of development in Formula 1 is unrelenting, with Allison admitting Mercedes have made changes to every part of the car, including areas such as the front suspension, in a bid to maintain their position at the top of the order.
"Across the entire car, across every part of its surface, we've made it new," said Allison. “We've found different ways of doing it. We have found improved way of getting downforce and performance into the car.
"Each one of them is small in isolation but they add up in their totality to something that is enormous. Last year's car was the quickest one out there. It won more races than any other and it was of course the championship winner.
"But last year's car would be utterly hopeless, it would be blown away by this one because of all that work by all those people over an entire year making modifications at every level. All of them are small but all of them are accumulating to a huge end result and a car that is just much, much faster."