Richard Thompson picks up his phone with a wet hand and calls back to England from a rain-soaked rural highway in Romania.

Something is wrong with the turbocharging system in Mark Higgins’ car.

The turbocharger isn’t spinning up to 125,000 rpm consistently. It needs reliable boost desperately at 6,800 feet above sea level to force air into the 2.0-liter flat-4 planted in Higgins’ specially built Subaru WRX STI Type RA, a car that has conquered a small, but growing, list of the world’s greatest roads and tracks.

The turbocharger’s deficit is just a few thousand rpm, but it’s enough that Higgins repeatedly called Prodrive’s chief rally engineer Thompson (“Tom-o”) on the radio from the Transfăgărășan highway just hours before to alert him.

Carved into the Carpathian Mountains, the spaghetti strand of Transfăgărășan pavement is consistently called one of the world’s greatest driving roads. It winds past Romania’s pastoral countryside where sheep frequently cause traffic jams.

“Intermittent failure in the turbo, Tom-o. Can you hear me?” Higgins calls, dancing through the dozens of hairpins as I ride alongside.

“With about 4 (kilometers) left, we lost boost,” Higgins says to me.

Something isn’t right.

Thompson calls the factory searching for three small, silver solenoids to fix the car. On July 10, late in the evening, Thompson calls on Howard Choularton to dash to the airport and ferry them on the 5-hour flight from London’s Luton airport to the middle of Transylvania.

It’s the last-ditch attempt to set a record that doesn’t yet exist, and the final scramble on a car several years in the making.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

Winter 2017

Prodrive’s unassuming factory near Banbury, England, is a squat, white, three-story commercial brick close to the M40 without any trees to absorb the din outside. Out front, the factory proudly flies the Union Jack whenever there’s a race or rally win, which is often.

The company employs more than 500 people spread across its motorsports, materials, and advanced technology programs. During winter, the outside temperature rarely reaches above 50 degrees—a far cry from summer in Romania.

The purpose-built Subaru WRX STI Type RA Special race car that sits in the Prodrive garage already has had 700 hours of work to prepare it for the rigors of setting world records.

Last year, Le Mans racer Richie Stanaway took the car to the Nürburgring-Nordschleife for a 6-minute, 57.5-second scrap over 12.9 miles.

In 2016, Higgins piloted the car to a record-setting lap of the Isle of Man TT circuit, during a 17-minute, 35.169-second brawl around the famed 37.7-mile motorcycle course.

Within the year, Higgins and Prodrive have their sights on a record beyond the scope of both previous runs: a 40-minute slugfest up the Transfăgărășan highway, which covers more than 50 miles and 600 turns.

Although planning for the run began in 2015, getting local authorities, course marshals, and permits has taken more than two years. With agreements now in place, Prodrive can begin to adapt the Subaru race car for the Romanian run, beginning with two engines—one primary, one spare.

Like the planning before it, Thompson calls the engine build up a “slow burn.”

Although Prodrive builds race cars for countless teams that compete all over the world—McLaren, Renault, Volkswagen, Aston Martin, to name a few—the manufacturing required to uprate a once-stock Subaru flat-4 EJ powerplant to more than 600 horsepower requires precision that only a few outfits can handle.

Prodrive outsources the machining required on the engine’s camshafts, pistons, connecting rods, pulleys, and flywheels to outside vendors that require at least 16 weeks to complete their work. The extreme punishment and speeds demand extreme precision.

“We’ve got to push the button on that hardware early,” Thompson says.

While the parts for the engines are out, the car largely sits, waiting for the chance for another feather in its cap—another race course and time to paint onto its hood.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

May 2018

Thompson and team board a flight for Sibiu, Romania, to analyze, pick apart, and distill every curve in the road like the grapes growing in the nearby backyards.

Each turn is measured for radius and surface quality, Thompson says. The measurements will not only inform engineers how to set up the car’s damping, but also its ride height and gearing.

Starting from the 6-speed, semi-automated transmission used for the Nürburgring attempt, Prodrive shortened the 4th, 5th, and 6th gears from the top-speed-ready ‘Ring run to a hairpin-intensive ‘box built for the Transfăgărășan.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

At 8,500 rpm, Higgins will hit just over 165 mph in 6th gear, down from the configuration prepared for Germany.

The transmission takes a week to configure. Thompson takes three more days to assemble the shift hydraulics, active center differential, and mechanical front and rear differentials that the Subaru will need.

To spot-check the critical electrical systems, Prodrive sends 400 volts through each wire—high voltage, but low current—to ferret out any corroded pins, connectors, harnesses, and broken wires in the Subaru that weighs just over 2,400 pounds.

“A car is made fast on the drawing board,” says Thompson. “It’s a level of checking those systems that gives us the confidence to tell Mark he’s getting into a safe car.”

Safety is crucial. More than 40 percent of Higgins’ run will be at wide-open throttle, as fast as the car can manage, barreling down skinny Romanian roads at more than 100 mph in many places—sometimes in clear daylight, or sometimes into a wall of soupy fog feet from the car’s face.

“I’ve never seen anything like this weather, in the way it can change,” Higgins says.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

June 22

Higgins winds his developing Subaru race car around small corners near the east coast of England on a sunny day. It’s relatively cool at Cadwell Park circuit, near Lincolnshire—only in the 60s, and the coolest day of the week—but the direct sunlight and ambient temperature help engineers tune the engine for maximum performance.

Details matter.

Thompson wants the surface temperature at Cadwell to be nearly identical to forecasts in Romania, which predict a road temperature of about 86 degrees. Even small variations in the surface temperature can impact how the engine powers through the track in the UK—and on the windy road in Romania.

The 2.2-mile circuit in England is unique among test tracks because the low-speed corners will help Higgins better gauge the balance of his car’s chassis, setting a stiffer rear end for oversteer through the corners. Thompson selects the circuit because it closely mimics the narrow track, tight hairpins, and surface condition he observed in Romania just a month ago.

But Cadwell Park is a far cry from the 50-mile gauntlet waiting in Romania.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

Higgins has relied on Thompson and Prodrive to prepare and adjust his race cars for decades, from the Isle of Man record run to rallies in China.

“Thirty years of experience from the World Rally Championship series means we have a broad spectrum of data,” Thompson says.

From that long history and data collected at Cadwell, Thompson and team finish their setup of the Subaru and prepare the car to ship to Romania. The attention to detail pays off.

“It’s fantastic. It’s how I remember the car,” Higgins would say later after practice runs.

“A happy driver on the wrong setup is happier than an unhappy driver on the right setup,” Thompson says.

Both car and driver sound and feel right for a run.

July 10—11:19 a.m.

Hundreds of sheep pour down the green mountain sides in Romania. Their bleats rise and fall like fog rolling into the gentle canyon that overlooks nearby towns. In the winter, only a gondola shuttles tourists and locals to the far-flung speck in the middle of Romania.

Today, the gondola and road are relatively motionless as onlookers await Higgins’ drive-by.

Higgins’ feet are a blur as the 47-year-old tap dances through gears, straights, hairpins, and the 17.6 miles he’s traveled to nearly the top of the mountain run he’s made so far.

He makes each turn with surgical precision and accuracy, but the Tuesday has been unexpected for many reasons.

The massive road, which is closed to traffic and nearly silenced for hours at a time, only burbles with waterlogged corners after hours of rain. Like every mountain climb, conditions at the bottom of the course can dramatically change toward the top. Romania’s sunny season has an unscheduled break for rain today, and Higgins is throwing himself through it at more than 100 mph in parts.

Instead of the Dunlop medium-compound racing slicks that Thompson and Higgins had planned on using from before the Cadwell test, they’ve resorted to using Michelin rally tires that are an inch narrower, harder, and not designed for hours-long runs at high speed on pavement. The rally tires heat up and degrade faster, aching for mud or rain to help cool the burning rubber.

From Higgins’ low perch in the race car he can feel the tires sloshing, burned past usefulness on dry pavement—four buttery wheels when sticky grip is critical.

Higgins’ tires aren’t the only issue.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 10—3:20 p.m.

Racing up the hairpin section, ahead of the rain but behind schedule, Higgins calls back to Thompson that the turbos aren’t responding the way he expects.

“Tom-o, can you hear me?” Higgins calls on the radio while I’m in the car.

The turbochargers aren’t delivering boost in the tight, winding hairpin section of the road, which lags the car by fractions of a second in the frantic scurry up the winding road.

Seconds add up, and Higgins says that the rain and the tires add seconds to kilometers, which adds minutes to the final run time.

Despite the lagging turbos and oncoming rain, Higgins reportedly sets a record up the Transfăgărășan hairpin section previously held by Ferrari.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 10—10 p.m.

After Thompson calls Prodrive for parts, Choularton, a customer support engineer at Prodrive, boards a plane at Luton airport bound for Romania with “a laptop bag, a toothbrush, and some boost valves” to fix the Subaru’s hobbled turbocharging system.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11— 3 a.m.

Choularton lands in Sibiu and engineers crack open the hood and start to work on the car’s turbocharging system.

Exhausted and in bed by 4 a.m., Choularton wakes up a few hours later for sightseeing.

“Sibiu is definitely one of the nicer places I’ve flown parts to,” he says.

His job is over, but Prodrive’s work has just begun for the morning.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—9:31 a.m.

Higgins, Thompson, Garrod, and Prodrive scramble to take advantage of clear weather along most of the 52.4-mile-long course.

The fastest tire they have brought with them are Dunlop medium-compound slicks, but pockets of rain and rivulets of water on the road force Higgins to try the rally tires one last time before his record attempt.

As he straps into his Subaru, Higgins gets last-minute information from Thompson before testing the Michelin rally tires.

The pair discuss changes and calibrations made to the car, down to the horsepower Higgins will get for the blitz down the backside of the mountain.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—9:46 a.m.

Higgins pulls in after a short run up a small section of the race course and opts for a compromise between the slick tires and rally tires.

Thompson and team cut small treads into the Dunlops—barely-there slits to wick some residual moisture away from the car but not enough to overheat the tires.

“It’s a brave man who goes on slicks alone,” Thompson says as Higgins pulls away.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—11:07 a.m.

Higgins reaches the Balea Waterfall on his record-setting attempt in the morning.

Only a few minutes later, the electrical system fails and Higgins and Garrod abort their attempt in the best weather his team have seen on the road yet.

“We need to bank a lap, get the data, and get on with the data,” Thompson says with frustration, and a clear run has so far eluded the team.

“I think this morning we learned we could go a lot faster,” Higgins says. “The indications are good for a nice run. The car felt great. The stresses on the car for 84 kilometers are immense. There’s not many cars that can do this…we’re just waiting for that magic window.”

The culprit is a third-party alternator that failed.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—2:24 p.m.

Thompson inspects the car’s vital systems for the last time before another record-setting attempt, likely the last. Planted in the driver’s seat with his laptop open, Thompson is looking for the last clicks in suspension that engineers can make to extract seconds from Higgins’ time.

He scours partial telemetry from partial runs from the morning and yesterday.

There’s no full run to draw from.

It’s not running blind, but it’s close.

Time to go.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—3:38 p.m.

Higgins leaves the start line for his afternoon run, his last shot at a clean record that has eluded him so far.

The pearl-blue race car whizzes into sight, past one, past two, past a half-dozen waypoints, a solitary blur against the lush Carpathian hills.

Hundreds of marshal workers, crew, spectators, cameramen—even a helicopter—watch.

The Subaru is a small speck against the green and white backdrop of hills and rolling fog. The sound of anti-lag fires off the mountain walls and reaches listeners like angry bees fighting for high-mountain air well before the car does. The pitch rises as the car approaches and breaks past like a cicada on a warm night.

His run is the apex of a journey that started years before, with an idea to set records on roads for other automakers to challenge later. It’s the meeting point of stage rally, spectacle, marketing, athleticism, and intense concentration.

With an unfettered run to the top of the mountain, a working alternator, and the steep climb of more than 5,200 feet now behind him, Higgins has a similarly long sprint to the finish line into the record books.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—4:19 p.m.

Higgins blasts by the finish line, perched on top of the Vidraru Dam that holds back the lake of the same name.

Higgins has set a record for a full run of the Transfăgărășan highway at 40 minutes, 58.8 seconds. He’s traveled at an average speed of 76.69 mph through 624 turns.

He doesn’t take much time to celebrate.

Even at the tall, checkered banner, Higgins is thinking of power delivery, tires, and weather.

It’s an achievement for car and crew, he says later, but he’s already planning for next time.

Subaru's record-setting run in Romania

Subaru's record-setting run in Romania

July 11—4:41 p.m.

Higgins calls Thompson from the finish line at the dam, more than 50 miles away, after the record-setting run.

“It’s not easy is it? Flippin’ heck it’s not easy,” Thompson says to Higgins on the phone. The two talk engine-management, tires, and weather for a couple minutes before they congratulate each other.

After he hangs up the phone with Higgins, Thompson thinks aloud of ways to go faster—just like Higgins.

“All we talk how to go faster,” he says excitedly. “We could use tire warmers, push the engine just that much more.

“Overall, I’m satisfied…but we can push everything that little bit more,” he says. “But we’ll definitely have a drink tonight.”

A record-setting Transfăgărășan finish is less a finish than it is a beginning.

Subaru provided travel and lodging to Internet Brands Automotive to bring you this firsthand report.