cars news 10: Subaru goes bob sledding in a WRX STI. Sort of

As its name suggests, the St. Moritz-Celerina Olympia Bobrun starts in the tony Swiss Alpine ski resort of St. Moritz—where perfectly tanned people in furs and skiwear tool around in Ferraris and Bentley Bentaygas—and winds downhill to the nearby village of Celerina. What the name doesn’t tell you is this mile-long ice chute drops 426 feet down the mountain and has 19 turns, including one called Horse-Shoe, a looping 200-degree hairpin so steeply banked it’s basically a vertical curtain of frozen water. A four-man bobsled, the Formula 1 rig of the sledding world with carbon-fiber bodywork and steel runners like bayonets, hits more than 80 mph on the Olympia Bobrun where riders momentarily endure 5 g as they rim fire around Horse-Shoe.

It’s the perfect place to drive a Subaru Impreza WRX STI, then.

And the perfect person to drive it? Well, he’s no stranger to slippery surfaces or Subarus or unconventional driving scenarios. A three-time British Rally champion, he’s also competed at World Rally Championship level in WRX STIs and holds the record for the fastest ever four-wheeled lap of the daunting 37.7-mile Mountain Course that hosts the legendary Isle of Man TT motorcycle races. And he also does some stunt driving. You would have seen him make an Aston Martin DB10 dance through the streets of Rome in the most recent 007 thriller, Spectre. The name’s Higgins. Mark Higgins.

Richard Thompson also knows a thing or two about slippery surfaces, Subarus, and unconventional driving scenarios. A 20-year veteran of British motorsport shop Prodrive, he’s worked on everything from World Rally STIs to Aston Martin Le Mans racers. He oversaw the preparation of the record-breaking car Higgins drove on the Isle of Man, and now he’s showing us around the STI that Prodrive has built to tackle the Olympia Bobrun.

Mechanical changes are relatively minor. Prodrive has fitted a tougher clutch and bigger AP Racing front brakes that could accommodate pads suited to working at cold temperatures. The fuel tank has been removed and replaced with a tiny 10.0-liter fuel cell, and all glass has been replaced with scratchproof Lexan. Inside is a full rollcage, an FIA-approved winged seat, and a side protection net. The wheels are narrow 5.5-by-16-inch alloys shod with ultra-skinny 135-section tires. Each tire bristles with 400 tungsten-tipped studs, each 0.3 inch long.

Bobsled Run in a Subaru WRX STI front wheels

Bobsled Run in a Subaru WRX STI wheels 02

Nylon skid bocks appear to be bolted to the sides of the front and rear bumpers. A closer look reveals they’re bolted to stout steel frames hidden underneath and stretching across the front and rear of the Subaru, and they are also attached to the body structure.

After watching bobsleds negotiating the Olympia mere weeks earlier, Thompson realized the trick to getting the STI down and up the narrow, twisting course would be to ensure it could survive pinballing between the rock-hard ice walls. The Impreza is 70.8 inches wide. The track, even after widening just for this stunt, is just 7.8 inches wider. Alhough the special brakes and the tires will give Higgins grip levels roughly equivalent to those of a regular STI on a greasy road, there’s going to be a lot of contact. The bracing is designed to stop the front and rear corners of the car collapsing under the impacts and to protect the wheels and suspension components from damage.

Horse-Shoe is the big unknown. Prodrive has done the math: The Subaru will have to be traveling at a minimum of 30 mph to make it around the wall of ice and not fall helplessly on its side. But the loading on the outside front wheel will be immense as the car transitions into the turn. Thompson has installed front springs that are 50 percent stiffer than those typically used on a snowy, icy mountain stage of the Monte Carlo Rally, and he’s inflated the tires to 50 psi to prevent them from literally peeling off the rims.

“Horse-Shoe is the key challenge for us,” Thompson says. “This is something no one’s done before.” It’s not just getting the Subaru into the turn on the downhill run that’s going to be tricky; the corner tightens slightly on the exit, and there’s a big wooden overhang designed to stop fast-moving sleds from flying off the ice and into the trees beyond. “We need to get the car to ride up the bank quite early and be coming back down again from the apex.” The chat among the crew is that Higgins has a 50/50 chance of making it.

After a morning’s shooting on the upper reaches of the Olympia, it’s time for Horse-Shoe. Higgins has already had a minor scare on the section just before the corner. The Subaru ricocheted off the ice so hard at one point it collapsed the wall. Fortunately, the impact sent the car bouncing the other way across the track as a 10-foot section of ice tumbled onto the access road leading up to St. Moritz. He’s quiet as he walks down to the entry of the turn and stares thoughtfully at the handful of florescent dots indicating the best guess at the line he needs to follow to make it around. The highest of them is a good 4 feet above his head.

The crew is hushed. The cameras are rolling. Higgins guns the Subaru past the hole he punched in the track wall a few minutes earlier, and aims it into Horse-Shoe. …

Check out the video to see what happens next.