Top speed boost and “reassuring” rear end key gains for Mercedes W15 F1 car

As the covers came off the squad’s new challenger at Silverstone on Wednesday, the scale of its design revamp was clear with an all-new chassis and a raft of aerodynamic changes on display.

But beyond the obvious visual differences, Allison said the key area of attention had been addressing the unpredictable rear end characteristics of its previous ground effect cars, which left Lewis Hamilton and George Russell uncomfortable at times.

“A big focus has been on improving the previous car’s unpredictable rear axle, which the drivers often referred to as spiteful,” he said. “We have worked on that to try and create a car that is reassuring to the drivers.

“At the beginning of a corner when you’re hard on the brakes and turning in, the rear needs to feel rock solid. And then as you get towards the apex, the car needs to feel progressively more nimble, and eager, to turn. We have been trying to build that into the car.”

Improvements in its handling characteristics have likely come from a combination of both aero improvements and mechanical changes – which includes Mercedes switching to its own version of a push-rod rear suspension around a new gearbox design.

Allison also said Mercedes has thrown effort at improving the aero efficiency of the car – especially when DRS is open – as this was an area that drivers were unhappy about last year.

“We’ve also worked hard to create a less draggy car, and to add performance in the corners,” he said. “There’s also been some housekeeping on areas in which we had room for improvement, including the DRS effect, and pitstop performance.

“We were always very good at delivering a pitstop in a repeatable time, which is the key thing for a pitstop. The repeatable time that we could do our pitstops in was still three to four tenths slower than the best teams, though. So hopefully we will have moved in the right direction there.”

With F1 teams operating under the cost cap, Allison also noted that the expense of a new chassis and gearbox casing meant it had to be mindful about not overspending on other aspects.

“A new chassis and a gearbox were standard for every year, pre-cost cap, and there’ll be several other teams who have done both things in a single year,” he said.

“But the cost cap does force you to pick and…