Porsche Boxster E First Drive

Imagine you're running along a country road at the wheel of a Porsche Boxster. One second, there's the glorious sound of a flat six-cylinder engine — a faint mechanical thrashing overlaid with the thrum of bass exhaust — behind your shoulders.

The next second, nothing. No engine noise. No exhaust. Nothing.

This is what happens when you deactivate Active Sound Management (ASM) on the Porsche Boxster E. Consisting of a digital recording and two speakers — one mounted within the cabin, the other within the rear bumper assembly — ASM has been developed to provide the plug-in electric prototype version Boxster with the simulated sound of its more conventional gasoline engine sibling.

A makeshift switch attached to the dashboard controls it all. Volume is linked to throttle load, so the harder you drive the louder it plays. Except, of course, if you decide to turn it off.

A Convertible Laboratory
You may have heard about the Porsche Boxster E. Created as part of the Intelligent Performance program that has already spawned the 911 GT3 RS Hybrid and 918 Spyder, the new two-seater is described as a toe-in-the-water exercise.

As well as its various testing duties, the new car has also been showcased as part of an electric mobility initiative being run by Porsche's home city of Stuttgart. Now, after some persuasion over recent months, the officials in Zuffenhausen have finally decided to let us sample its all-electric roadster.

Currently, there are only three Boxster E prototypes in Porsche's test and development fleet. Two of them, including the car we drove, use a single electric motor and rear-wheel drive. The third prototype runs two electric motors and a more complex four-wheel-drive arrangement with front axle components brought over from the 911 Carrera 4.

They're essentially rolling research laboratories that are being used to gather data that will be used to shape Porsche's electric car plans. "We had already developed gasoline-electric hybrid solutions for a number of models. The next logical step was a full electric car. We haven't been pressured by market considerations or anything like that. It is a natural progression in the field of alternative drive systems," says Michael Dimitrov, head of advanced engineering.

Why the Boxster?
According to Porsche, the midengine roadster provides the best packaging solution of any of its existing sports car models. It allows the battery to sit low in a mid-mounted position to get the center of gravity down. The Boxster's low curb weight was also a decisive factor in giving it the nod over the 911, according to Dimitrov. "The lighter the base car, the more scope you have in terms of performance and range," he says.

The conversion from conventional gasoline power to electric propulsion has not altered the Boxster's basic architecture in any obvious way. The inner body structure is virtually unchanged, as is the complete outer body. If it weren't for the silver and orange "Intelligent Performance" graphics Porsche's marketing department has seen fit to slap on the car, not to mention the lack of tailpipes at the rear, you'd be hard-pressed to pick it apart from the regular model.

More than the performance, though, it's the completeness of the Boxster E that's most satisfying.

Sitting in the space usually taken up by the Boxster's mid-mounted flat six-cylinder engine is a battery pack sourced from U.S.-based A123 Systems. It's a lithium-ion unit that consists of 340 individual cells that provide 29kWh of power capacity and a total output of 240 kW. The entire pack weighs 752 pounds and its temperature is kept in check by a modified version of the Porsche roadster's existing cooling system, which relies on two radiators mounted in the nose section.

Charging is done through a plug mounted in the same place as the traditional fuel filler in the right-hand front fender. There are no figures for the North American 110-volt system, but Porsche claims a recharge time of eight hours on the 240-volt European network. Kinetic energy created under braking is also used to top up the battery on the run. A whole range of electronic systems and wiring, meanwhile, occupies the space normally devoted to the Boxster's fuel tank up front in the nose.

Remove Engine, Add Motor
In the rear-wheel-drive prototype we drove, the electricity stored in the battery is used to power a single electric motor mounted at the rear as part of a modified rear axle. Sourced from parent company Volkswagen, which uses the same brushless unit in the Golf e-motion, it develops a maximum 121 horsepower — or less than half of what the Boxster's 2.9-liter engine throws out. Peak torque is rated at 199 pound-feet, all of which is available the moment you introduce your foot to the accelerator pedal.

The new driveline weighs more than 880 pounds in total, taking the Porsche Boxster E's curb weight to a claimed 3,483 pounds. There has been no attempt to lighten the car's structure through the use of carbon fiber or other exotic materials. "The focus is very much on the electric system rather than construction. We've got other programs handling that aspect of development," says Dimitrov.

There are, however, some low-cost measures aimed at keeping the pounds off, including the use of carbon-fiber-backed shell seats, lightweight 19-inch wheels and carbon-fiber disc brakes — all of which are offered as optional equipment on the Boxster. Still, there's no disguising the fact that it tips the scales some 408 pounds beyond its gasoline engine sibling.

Other changes? Porsche has ditched the current Boxster's hydraulic steering system for a new electromechanical system that's set to appear on the third-generation version of its roadster due out next year. The standard air-conditioning compressor has also been swapped for a more efficient unit that uses less electricity.

Needs Some Noise
We took the Porsche Boxster E out on to the streets of Stuttgart and over some more challenging roads through the surrounding countryside. In general terms, it is not unlike many other electric cars we've driven of late — smooth, efficient and straightforward to drive. But with a limited range of just 106 miles on a fully charged battery, you've always got to keep an eye on the miles-to-empty gauge.

Even with a modest amount of throttle, the new Porsche accelerates away from the traffic lights smartly, hitting posted limits without feeling strained. There's sufficient low-end torque from the motor in back to give the zero-emissions two-seater a nice flexible delivery that ensures it never gets left behind at city speeds.

Whether you choose to activate the ASM is really a matter of the conditions. In traffic, the distant sound of the engine is rather superfluous and, at times, a distraction. But find a more secluded road where you can stretch the Porsche Boxster E and it suddenly seems odd to run without it. Think what you will of a simulated sound recording, but the synthetic thrash of engine mechanicals and an accompanying thrum of exhaust certainly adds to the entertainment factor.

Less Weight Would Be Good, Too
In the end, though, the rear-wheel-drive Boxster E just doesn't possess the power to really overcome its weight. Beyond 50 mph, the level of acceleration begins to trail off quite dramatically as the efforts of the electric motor meet their physical limits. Porsche claims zero to 62 mph in 9.8 seconds and a top speed limited to just 93 mph — although the prototype we drove was restricted to an even lower 75 mph.

On the strength of its on-paper specifications, the four-wheel-drive Porsche Boxster E prototype would seem to go some way to fulfilling our desire of greater performance. With a second electric motor mounted up front and providing additional drive to the front wheels, Porsche says it accelerates from zero to 62 mph in just 5.5 seconds — just 0.2 second shy of the Boxster S. It's also claimed to run to a limited 120-mph top speed.

And because the second electric motor also acts as an alternator, providing the basis for additional recuperation of kinetic energy, Dimitrov reveals that the four-wheel-drive prototype boasts the same 106-mile range as the rear-wheel-drive prototype. It certainly sounds more like a car worthy of the Porsche badge.

The Complete Package
More than the performance, though, it's the completeness of the Boxster E that's most satisfying. It might have been a prototype, but the car we drove felt remarkably well built. Dynamically, it lacks the intensive communication you receive in the gasoline-engine Boxster, but it is still among the more engaging electric cars we've ever come across — up there with the likes of the Audi R8 E-tron, for sure.

The steering, uniquely tuned for the Boxster E, is lighter than we expected in terms of weighting but is quite direct, providing great agility given the heavy lump of battery that sits just behind your shoulders. The handling is also impressively tidy, with tight body control and a neutral nature to the way it corners, although admittedly we weren't pushing the limits. And the brakes offer good levels of feel and sensational stopping power. Like we said, complete.

It's hard to say when the zero-emissions technology used in the Porsche Boxster E will migrate into a production car. For that to happen, Porsche boss Mathias Muller must first decide whether it is wise for a company with such a rich tradition in conventional gasoline-engine sports cars to follow the likes of Tesla into the electric car ranks. Then again, that decision might be made for him. Either way, Porsche will be ready.

Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.