250-mph McLaren dials up innovation

The Speedtail is the fastest vehicle in McLaren Automotive's portfolio of performance cars. And in the small exotic market segment, where racetrack speed and body-jolting acceleration are the fundamentals of sales and brand recognition, it wasn't enough for engineers to make the hypercar "fast" — they had to make it "faster."

Faster than competitor models. Faster than they thought they could achieve.

Developing the $2.25 million car was an exercise in pushing boundaries.

And the resulting Speedtail hybrid bristles with innovations — from retractable cameras to bendable carbon fiber — aimed at one goal: reducing speed-sapping drag.

And getting the 3,153-pound limited production sports car to hit 250 mph took some fancy engineering and design footwork, assures the Speedtail's architect, Andy Palmer. "It's a lot more than putting 2,000 hp in a car and just hoping it's going to go down a runway," said Palmer, vehicle line director for McLaren's Ultimate Series.

How does an exotic performance automaker — a brand reliant on being recognized for its achievements in velocity — make a fast car move even faster? Here are the ingredients:

The Speedtail's beating heart is a 4.0-liter twin-turbocharged V-8 mated to an electric drive unit. Combined, they put out a thunderous 1,055 hp. The powertrain is complemented with an energy-dense but lightweight battery pack.

The engine features technology that has evolved from McLaren's first hybrid hypercar, the McLaren P1. The electric motor, which uses Formula E-derived technology, generates more than 308 hp and helps propel the Speedtail from standstill to 186 mph in sub-13 seconds.

"It's almost like a nitrous boost," Palmer said.

The hybrid powertrain in the Speedtail is about optimizing acceleration, not eking out a few more miles of driving range.

"We maximize ourselves on the natural power of the internal combustion engine, and then we bring in the hybrid power to really push through and keep the car going right through that difficult period above 230 miles an hour," Palmer said.

"We couldn't punch through that sort of air forces without having the hybrid power."

The need for speed drove all aspects of the Speedtail's development.

It is designed to be "a fast road car, a GT, an A-to-B," Palmer said. "We're not looking for downforce, we're looking for low drag. And the challenge we have is the faster you go, the more drag you get. "

Solving that drag led to the Speedtail's signature long-tail, teardrop shape.

"We had to start thinking about, how is the air going to behave?" Palmer said. "That really sets up the way the car looks — from its nose into the ducting on the hood, which feeds into the wheel arches."

Managing the airflow led the design and engineering teams to get creative.

The front wheels sport carbon-fiber aero covers to reduce turbulence — and that dreaded drag — created by the spinning wheels. The 20-inch covers do not rotate with the wheels, creating a flat surface that smooths airflow and keeps the passing air snug to the body of the car.

"The fixed wheel covers that we took a lot of criticism for when we put it out there are needed to keep the flow linear and attached as it transitions down the side of the car," Palmer said.

McLaren's engineers also swapped the car's sideview mirrors for a pair of low-profile, high-definition digital cameras that glide out of the doors when the vehicle ignition is activated. When Velocity mode is turned on, the cameras retract, reducing drag further still.

The digital cameras also provide a wider field of view than traditional mirrors. The video feed is displayed on screens positioned at either side of the instrument panel in front of the driver.

It was no simple engineering detail.

"I would never do it again because they are an absolute pain in the arse to get right," Palmer said of the technology. It required adding a monitor, cameras and "all this software when actually an optical mirror that's worked well for 70 years can do just as good a job — and it's lighter."

"But," he said, "they are there so we don't have two large poles out in the flow of the air."

In their pursuit to maximize aerodynamics, engineers drew inspiration from experimental NASA jet technology. To add stability and create downforce, the engineers developed a pair of airplanelike ailerons made of "movable carbon fiber" that act as spoilers.

"We didn't want a P1 wing; it didn't look right," Palmer said. "But we still have that need to trim the car at speed to get a little bit of stability."

Unlike traditional hinged ailerons, the Speedtail's are integrated into the carbon-fiber bodywork of the car's rear. There is no separate moving element, which would have required drag-inducing joints.

"They were difficult to get right," Palmer admitted, and "took a lot of work from the engineers and our suppliers. But it's quite a cool little feature."

Building a car that can reach 250 mph in wind tunnel simulations is one thing. Hitting that number when the rubber meets the road is quite another.

To prove the Speedtail's performance, McLaren turned to Indianapolis 500 winner and McLaren chief test driver Kenny Bräck.

On a winter day in 2019, Bräck pushed the Speedtail to its limits at Cape Canaveral, Fla. Using the space shuttle landing runway as its test track, the car hit 250 miles — in more than 30 test runs.

Palmer marvels at the guts it took for Bräck to do it. Not to mention the tires it took.

McLaren worked with Pirelli to design a tire sidewall that could withstand triple-digit speeds while still offering a comfortable ride at more sensible speeds.

"To make the tire survive 250 miles an hour, the sidewall had to be incredibly stiff to keep it from separating," Palmer said. But it also had to be compliant at lower speeds, "so you're not running on a band of rubber that makes the ride jarring," he said.

The Speedtail tire took months to develop and is emblematic of the challenges of McLaren's approach to vehicle development. Everything on a McLaren — from the lightweight titanium wheel nuts to the carbon fiber — is tailored to the car, Palmer said.

"That way we can guarantee the quality, and we can ensure then it's fit for purpose," he said. "That's why it takes us a good couple of years to design a car."

But it also means engineers are figuring out technical innovations during vehicle development — leaving little room for trial and error.

"In developing Speedtail, we didn't know how to do the mirrors, we didn't know how to do the tires, we didn't know at the start how to make the carbon fiber flex," Palmer said. "We did all these in parallel with the project, which puts a lot of stress onto the team because if that goes wrong and we can't prove it out, then we could have a concept that doesn't work."