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Porsche 911 Carrera Vonnen review: unofficial hybrid driven

Published:23 April 2019

911 Vonnen hybrid
  • At a glance
  • 4 out of 5
  • 5 out of 5
  • 4 out of 5
  • 4 out of 5
  • 4 out of 5

By Kyle Fortune

CAR contributor and fan of going fast - on four wheels and two skis

By Kyle Fortune

CAR contributor and fan of going fast - on four wheels and two skis

► Unofficial hybrid 911 driven
► $75,000 for 148bhp and 148lb ft
► Can be fitted to any 911, Boxster or Cayman

We all know Porsche plans a hybrid 911, but Silicon Valley firm Vonnen has beaten Stuttgart to it.

A slight electrical note can be heard over the familiar sound of the 3.4-litre flat-six of this early 991-series 911. Glancing down at the speedometer underlines what’s been happening. This not an ordinary 3.4 Carrera, it’s coming with a little bit of hybrid assistance.

The Vonnen looks like a normal 911 from the outside

Electrical surge…

Electric motor assistance specifically, Vonnen, a Silicon Valley firm, has worked out how to pancake an electric motor between the engine and gearbox in this 991 Carrera. It’s PDK, rear-wheel drive and a 3.4-litre, naturally aspirated water-cooled flat-six in this car, but it could be manual, turbocharged, four-wheel drive, standard, tuned or even air-cooled. Hell, Vonnen reckons the hybrid drive can, with a bit of tweaking, be fitted to any 911 right back to 1965. Boxsters and Caymans, too.

That means Vonnen’s beaten Porsche to the road with an electrified 911. The aim here is additional performance rather than economy, but it’s achieved it without impacting on the standard emissions - that being rather important in Vonnen’s California home - and only adds, about 77kg in weight. That’s pretty low, largely because it’s removed the weighty flywheel and starter motor - starting, and stop-start done with the electric motor.

How it’s done: the tech bit

There’s a compact battery pack under the boot floor, while the Vonnen Shadow Drive, or motor generator unit between that engine and gearbox. There are cooling circuits for that motor, as well as the power inverter that sits under the rear window. That’s all that marks this 911 out visually, if you ignore the orange wheels and Vonnen stickering, the motor adding up to 148lb ft of torque and 148bhp depending on the driving mode you’re in.

The battery pack

The performance difference

That’s enough to turn this modest Carrera into something significantly quicker, though it’s so seamlessly integrated to have you initially wondering if it’s working. Until you look at the speedometer, that is. It’s quick then, and so linear, in Street mode the torque increase being 92lb ft when you’re asking 40% throttle, Sport upping the ask at your foot to between 65% to 95% push, adding 81lb ft when you do so. 

Pop it into Overboost - done like all modes via the dashboard-mounted Bluetooth-tethered smartphone app - and you get the full 148lb ft for maximum performance. Do that and the acceleration is vivid, oddly reminiscent of a pure EV in its surge, but piggybacking that of a standard 911 to create a supremely well integrated whole.   

Unofficially brisk

There aren’t any official numbers yet, but it feels like it’s tapping on 991 Turbo quick, yet for all the additional performance there are no apparent compromises. The system is self-charging, scavenging back power from the engine when it can, the engine braking feeling similar, too, indeed its operation so neatly integrated as to be a bit too subtle at times.  

Hybrid power is controlled from the dashboard

Sharper low-rev electrical assistance for that instant hit you get from pure EVs at lower speeds might make it easier to justify the sizeable $75,000 outlay you’ll need to find if you want your 911 battery boosted.

Is there an EV-only mode?

And no, it’s not able to run on electricity alone, this a performance upgrade, not one that allows you to sneak you into ULEZs in your favourite 911. That might come in the future, but for now it’s not possible. What is undeniable is that it’s got real potential for those wanting more performance without the compromises that accompany more conventional tuning.

This is a hybrid application that’s enjoyable rather than earnest, and one that allows you to claim you’ve a hybrid 911 to your greener-leaning friends, without actually revealing that it’s actually all about going quicker…

Specs

Price when new: £57,705
On sale in the UK: now
Engine: Electric motor, adding 200Nm and 150hp to any flat-six
Transmission: Here - 7-speed PDK though it can be fitted to any 911 transmission
Performance: N/A
Weight / material: Additional 77kg over the donor car
Dimensions (length/width/height in mm): 4491/ 1808

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  • Porsche 911 Carrera Vonnen review: unofficial hybrid driven
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By Kyle Fortune

CAR contributor and fan of going fast - on four wheels and two skis

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