Why You Can't Beat Light Weight

Motor 1

3 days ago

We've gotten really good at cheating physics. Even though cars are getting much heavier, the technology to hide their weight is getting much better. Adaptive and active suspensions, torque vectoring, electronic differentials, traction and stability controls, and ever-better brakes and tires all make cars seem so much lighter than they are.
A new BMW M3
weighs around 4,000 pounds, but you wouldn't believe it by the way it flits into a corner on track.
But, in my experience, you can't actually beat physics. We call them Newton's
laws
for a reason, and driving a truly lightweight car brings that into sharp focus.
Welcome to
The Rabbit Hole
, a bi-weekly column where Senior Editor Chris Perkins explores his latest obsession with automotive technology. He speaks to the best in the business to understand how cars work and what the future of the automobile looks like.
Photo by: Chris Perkins / Motor1
This car is truly lightweight. It's a 1966 Porsche 912 restored by the Hungarian company
Kamm Manufaktur
. Its founder, Miklós Kázmér, bought a 912 to do what many do with these cars—rip out the standard flat-four and put a hot-rod 911 engine in it.
But the lower weight and better-balanced weight distribution of the four-cylinder 912 charmed him, and he wondered how far he could take one. The answer is 'very.'
Kamm claims an astonishing 1,654 pounds for this 912C. That's around 700 pounds lighter than a new Miata, and this car is in something of a 'touring' specification, complete with electric air conditioning that works astonishingly well. The 'C' in 912C stands for carbon fiber, and most of this car's body is made from the stuff, all but the roof and rear fenders. Kamm will build you a full-carbon car, which knocks off an additional 100 pounds.
'I knew that from a 2.0-liter engine I won't be able to get humongous power without turbocharging,' Kázmér explains. 'So I had to reduce the weight.'
Kázmér's not the first to face this problem. Every race-car constructor, when up against an effective power limit, has to look elsewhere for speed. Colin Chapman's obsession with weight savings came from not having access to the most powerful engines in the early days of Team Lotus.
Photo by: Chris Perkins / Motor1
Two liters is about as big as you can go with a Porsche Type 616 flat-four before you end up with something that simply doesn't want to rev. Don't forget, this is a pushrod engine. Kamm's gone all out with this flat-four, with a claimed output of 190 horsepower at 6,800 revs, well over double that of the 90-hp original. It's got throttle bodies and a modern engine management system with two drive modes, normal, and "Drive Me Crazy," which sharpens the throttle map and opens up exhaust valves.
It's a very powerful engine considering its roots, but it's also playing in a world where 911 restomods have well over 400 hp. To get the most out of the whole package, you need to cut weight.
On an early summer day outside New York City, the thing that's immediately apparent with the 912C is the ride quality. That's, of course, by intention—Kázmér wanted something of a touring car, and the 912C features fancy electronically adjustable TracTive dampers—but it's also a natural byproduct of low weight. Engineers often talk about the virtuous cycle of reducing weight.
Less weight means less work for the suspension, so you can use less spring, damper, and anti-roll bar. It also means you need less tire, which itself cuts weight and improves ride quality, and the same with brakes. The benefit of reducing weight compounds on itself.
Photo by: Chris Perkins / Motor1
I took the 912 on roads I know well. These suburban country roads can get choked up with a bit of traffic, but they're not too far from New York City, and many have a fairly generous 55-mph speed limit. They're roads I've driven in my own car—a 2017 Volkswagen Golf GTI—friend's cars, and many loaners from automakers.
No car with any sporting pretensions has made the bumps and imperfections here seem so insignificant. You get up to sections of road where you instinctively wince, knowing what it's going to feel like when you roll over. But there's no need in the 912C. Even with the adjustable dampers in their stiffer settings, it just sort of floats over them.
This, I think, is where you really feel the difference. That M3 I mentioned at the start might often seem to defy its weight, and it's got nice damping, but it's stiff. You feel how much work the suspension is doing to keep the mass in control. Hell, even my GTI is not a heavy car, but it can't do what the 912C does. Fully active suspension systems like those from Ferrari and Porsche get a lot closer to what a truly lightweight car can do, but there are often moments when you feel the weight.
Modern suspension, brakes, and tires do an extremely good job of controlling weight, but it's impossible to fully conceal. The first time I drove a Ferrari Purosangue, I was blown away by its incredible body control, and most of the time, I forgot I was in an SUV. But, under braking, you suddenly have the sense that you're in something very heavy, and that the car is doing a ton of work to control it. I had a similar sensation track testing a Taycan Turbo GT, but this might've been exaggerated from the unrelenting speed of that particular car.
That moment never comes in a car like this. And it's not like the 912C is a slow thing either—the power-to-weight ratio is about the same as that of a Porsche 718 Cayman S. You wouldn't have trouble keeping up with a new Cayman, too, with the 195-section 200-treadwear Yokohama tires providing excellent grip, and oversized brakes bringing the 912C to a quick halt.
Photo by: Chris Perkins / Motor1
Photo by: Chris Perkins / Motor1
Photo by: Chris Perkins / Motor1
Kamm's car shows off its lightweight bona fides proudly. The hood and front fenders have a beautiful transition between exposed glossy carbon fiber and paint that's so smooth you can't feel it by hand. The engine lid is held down by two motorsport-style catches, and its hinges are a beautiful drilled aluminum. There's no strut or anything to hold it up, either.
Inside, there's gorgeous carbon-fiber trim for the bespoke door cards, dash, and seatbacks, but it's not spartan in here. There's also green leather in this particular car, and niceties like a hidden Bluetooth audio system, a wireless phone charger, and the previously mentioned A/C system.
Of course, you'll have to pay very handsomely for this lightweight, €350,000 ($410,000) plus the cost of a donor car. Way too much money, unless you've got a very specific itch to scratch.
Photo by: Chris Perkins / Motor1
But it is a thing to experience, and a good reminder of what weight savings can do for a car.
It used to be easier to get a lightweight car. The original Mini weighed barely over 1,300 pounds, and that was considered a small family car. Now, a lightweight is a specialist sort of thing. You need a Miata, or if you're lucky enough to live where they're sold, an Alpine A110. Both are around 2,400 pounds, which, while low by today's standards, isn't anything like old-school lightweight, but both do have that wonderful fluidity of a true lightweight.
All of these cars, from the $30,000 Miata to the $400,000-plus 912C, reveal an important truth—you can't outrun the law. Newton's laws, at least.
More From the Rabbit Hole
Subaru Made the World's Only Twin-Turbo Flat-Four. It Was Madness
Why Carbon-Ceramic Brakes Are Expensive. And Why They Might Be Worth It
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