It was while sat in a ditch after skidding off an icy road in Sweden that Mercedes-Benz engineer Frank-Werner Mohn first got the idea that would lead to electronic stability control. Many of us would simply be fretting that we were trapped, and had just crashed a precious engineering prototype, but not Mohn.
When he got back to base (and had finished explaining things to his bosses), he sketched out his idea. Back in 1989, many cars already had anti-lock brakes (ABS). Mohn’s idea was for an onboard computer to communicate with the ABS, using braking pulses on each corner to straighten out the car in a skid.
Mohn went one further too – another computer would constantly monitor the car and, if it sensed something untoward happening, the system would automatically pulse the brakes to actually prevent a skid happening in the first place. It was inspired; he was thus set to work with component supplier Bosch to make it a reality.
First they needed a sensor that could detect sideways movement. A gyro sensor would do: Mohn bought a toy helicopter and proved the theory would work – then secured company funds to buy a faster, more capable gyro sensor… which came from a scud missile.
He did all this despite being mocked by colleagues. But they soon went quiet when top Mercedes-Benz execs tested one of the first development cars on an icy lake in 1991. A particularly nervous executive skidded off at the very first corner when driving a car without ESC – but then was able to lap almost as fast as a racing driver with it engaged.
The argument was won; the board instantly approved it, and it made production in the S-Class luxury car in 1995. And then, two years later, a Swedish magazine famously tipped over a Mercedes A-Class during the ‘moose test’ swerve manoeuvre. What was thus top-line technology instantly became the solution to the firm’s high-profile dilemma: ESC put the A-Class back on an even keel and, soon after, became standard across the range.
Mercedes and supplier Bosch couldn’t build systems fast enough and so, in something of a bittersweet move for Mohn, it handed over its patents to rivals, for free, so they too could build the life-saving systems. If the engineer was miffed, though, the payback soon came: German authorities started reporting a reduction in fatalities in cars fitted with stability control. Mohn was saving lives.
Today, some reckon ESC could have saved 1 million lives, particularly as it’s now mandatory fitment to all new cars in many major markets, including the UK. A demonstration on an icy lake in Sweden helps remind us just how clever the technology is; luckily, all we have to hit is banks of snow, because with ESC off, we’re hitting them almost constantly. With it on? We hit nothing.
Then someone has an idea. Take Mohn to the place where he crashed his test Mercedes and came up with the idea of stability control. The engineer can’t remember exactly where it was – but he has a photo of the crashed car, complete with the liveried tow truck that saved him. Someone tracks down the company, and asks them for help.
The business owner is immediately onto it. He finds the original driver’s son, Tommy Bjurstrom – who, by chance, rode with his dad on that day in 1989 to recover this flashy Mercedes. And Bjurstrom, after looking at the picture, knows exactly where the crash occurred. So we follow him a few miles up the road until we stop next to a large ditch.
Mohn and Bjurstrom embrace. What happened here three decades ago has saved a million lives or more. “In my heart, I was wounded because it was my invention and it was given away,” admits Mohn. “But, of course, I now see the best decision was… to make it available to everyone, to spread it out to all cars.” Literally million should be thankful.