Porsche InnoDrive

The Porsche that (mostly) drives itself

Photo: Porsche InnoDrive 1
February 26, 2015

It takes all of five minutes for me to trust Porsche’s InnoDrive. My destiny is now in the digital hands of a half-dozen sensors and instruments tasked with ensuring the vehicle maintains an appropriate and safe velocity among the traffic navigating the public roads surrounding Weissach, Germany.

Even though I am in the driver’s seat, the Porsche sedan is accelerating, maintaining speed and braking completely by itself. My only role is to clutch the thick three-spoke wheel and steer. Even though the lead engineer of the program is with me inside the vehicle, the experience is more than a bit unnerving.

An autonomous car, in the simplest of terms, is a passenger vehicle capable of sensing its surrounding environment and safely navigating without any human interaction. While the result seems rather straightforward, the process of actually building an autonomous vehicle that can drive itself at speed has dodged engineers for decades—especially if the self-driving car is required to interact with other human-piloted vehicles on the same road.

Photo: Porsche InnoDrive 2

Porsche, like many automakers, has been working on autonomous programs for many years. But unlike most of the other manufacturers, who appear obsessed with developing a vehicle that cuts the driver completely out of the picture, the German automaker has been focusing on improving safety and fuel economy while leaving the most important part of the driving experience—steering—untouched.

Maximum Overdrive

The InnoDrive program was launched in 2007 as a way to improve energy management, say the original plans. Porsche’s engineers reasoned, quite accurately, that humans overcompensate on the accelerator and brake pedal and consistently fail to properly anticipate conditions ahead of the vehicle—we drive sloppy. If there were a way that computers could control the longitudinal axis of driving (acceleration and deceleration), the end result would be improved efficiency. The lateral axis (steering) would be left to the human, the engineers decided, to retain a basic level of motoring enjoyment.

Photo: Porsche InnoDrive 3

Seven years after the program’s initialization, I find myself standing next to a first-generation Porsche Panamera Turbo S outside a nondescript building in Weissach. A 550-horsepower sedan, capable of hitting 60 mph in 3.5 seconds, isn’t what I was expecting as an InnoDrive test platform, but my hosts explain that this is Walter Röhrl’s old road car (complete with his backlit signature sill plates beneath each door), which was donated to the program after the celebrated race car driver was done with it—enough said!

While Röhrl’s former Panamera Turbo S appears virtually stock from the exterior, the vehicle has been modified extensively to accept a full array of InnoDrive sensors. Each is tasked with providing a stream of pertinent data to the InnoDrive processors, which then send the appropriate commands to the throttle and brake. All told, there are no fewer than six different sources of input guiding the computers.

The first is long-range radar, mounted in the lower front fascia, which is responsible to observe the driving behavior of the preceding traffic. Second is a camera, mounted high on the windshield, to read road signs for speed limits and keep an additional eye on the surrounding traffic. Third is a digital road map, which is loaded with pertinent information including surveyed speed limits and details about the slope and curvature of the roadway. Fourth are a series of vehicle sensors that monitor road conditions, vehicle load (weight and balance) and vehicle conditions (cornering and accelerating forces). Fifth are the on-board computers measuring vehicle efficiency. Last is the console switch that allows the operator to select a vehicle setting (Eco, Dynamic or Comfort) to alter the powertrain response and performance.

Photo: Porsche InnoDrive 4

Porsche asked me not to photograph the trunk compartment, simply because it is a work-in-progress chock full of unattractive black boxes and wires. The balance of the passenger compartment is mostly stock, with a few exceptions. Most visible to the operator is the gauge marked “Dynamic,” which occupies the spot formerly reserved for the speedometer. The new display serves as combination speedometer and visual confirmation that the vehicle “sees” the lane and the traffic conditions ahead. Think of it as an oversized Adaptive Cruise Control (ACC) monitor with a lot more information.

In addition, the damper button on the console has been covered with a handcrafted black sticker with the aforementioned vehicle settings in white lettering. Last, but critical during the program testing phase, is a big red kill switch—easily accessible by any of the four passengers—that will rapidly disable InnoDrive and return full control to the human driver.

A Self-Driven Road Test

Photo: Porsche InnoDrive 5

After a short briefing, I climb into the driver’s seat of the Panamera and start it up. The turbocharged V8 rumbles to a familiar growl, as expected, so I move the shift lever into drive and pull onto the public roads. I drive about 100 yards and then initiate InnoDrive with the ACC stalk—things quickly get a lot more interesting.

The Panamera immediately “locks” onto the vehicle directly ahead, maintaining a safe cushion of separation as it does with ACC. Then, unexpectedly, the leading vehicle turns off the road. Instead of accelerating aggressively, as it lacks a target to follow, the InnoDrive system accelerates to the posted speed limit (simultaneously displayed digitally on the dashboard) and holds it. I steer normally as the Panamera holds the posted speed around a series of corners and bends.

Ahead, the road opens to the countryside with high speed limits (a speed limit sign appears digitally in the Dynamic gauge, so the driver may verify the system’s intentions). A mere seconds later, the exhaust note of the Panamera increases in volume as it accelerates to the new posted speed. Now moving at a decent clip, I spot a tight right-hander and increase my grip on the wheel (my right foot instinctively hovers over the brake). Even though the Panamera doesn’t slow as much as expected around the bend (braking reduces efficiency), I don’t flinch—the Porsche jets around the corner perfectly!

I continue to steer the Panamera along the prescribed route for a good 20 minutes with my feet on the floor and my mouth agape in utter amazement. Out of curiosity, I toggle through the different driving modes (Dynamic is aggressive, while Eco mimics hypermiling) and deliberately turn in sharply in some corners to see how it reacts (the g-force sensor will automatically apply the brakes if cornering forces are too high). My take is that it works exceptionally well—decidedly better than most humans. And proving its original efficiency theory, Porsche says InnoDrive delivers about a 10-percent improvement in fuel economy compared to the average driver.

To be more specific, strength is its ability to anticipate and predict energy requirements in advance. It knows how much throttle is required to crest the hill at the speed limit without having to unnecessarily brake on the other side, and it coasts towards an upcoming traffic condition that will require a complete stop. Future models of InnoDrive will even communicate with traffic lights, so the vehicle won’t accelerate towards an impending red light.

Today’s iteration of InnoDrive works nearly perfectly on the open highway and on country roads, where all of its instruments are at ease. Back in Weissach, however, I had to stab the brakes when a pedestrian unexpectedly jaywalked in front of the car—that is a scary obstacle! As of now, its sensing system isn’t intelligent enough to tackle a traffic-laden urban environment with stop signs, traffic lights and roundabouts (today, the operator has to press the accelerator gently to tell the system that it is safe enough to move). But that will come with time, of course.

I’ll admit to a certain level of skepticism when I first learned of InnoDrive—as an enthusiast, I want full control. But an afternoon with the semi-autonomous system proves to be informative and enlightening. The architecture is in place, it works and—most importantly—it earned my trust. While I will likely be a late adapter, much preferring to heel-toe my way around a twisty canyon, I foresee plenty of advantages and opportunity for Porsche’s InnoDrive when the technology comes to market in the near future.

Also from Issue 227

  • Fifty years of the Porsche 911 in the U.S.
  • Björn Waldegård’s 1970 911S/T
  • A rare orange pre-A 356 Continental Cab
  • Market Update: 912 & 914
  • The 928 is a lot of car for the money
  • Porsche’s most uncompromised sports car?
  • Nuccio Bertone’s German-Italian concept cars
  • Porsche’s “brand immersion experience”
  • The Carrera GT’s project manager speaks
  • A look at how turbos make big-time power
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