An ingenious VW-based plug-in hybrid that drives well, but it’s a good three years away
Richard Bremner Autocar
10 November 2011

What is it?

Think of the VW Group’s TwinDrive powertrain – found in this Seat Leon TwinDrive Ecomotive test car - as three low-emission propulsion systems in one: a pure EV, a series hybrid and a parallel hybrid. And with a plug-in capability besides.

Sound complicated? It is, and costly to make too, but it’s a system that allows this experimental Leon to turn in a spectacular 166 official mpg while emitting a mere 39g/km of CO2. It can also travel 32 miles on electric power alone, and has a potential range of over 550 miles.

So, how does it work? Under the bonnet is a standard 113bhp 1.4 TSI petrol engine. Bolted to this are a 40bhp generator, a clutch, a reduction gearbox and an electric motor, also of 113bhp.

What’s it like?

When the Leon starts, it sets off electrically. But if hard acceleration is required at low speeds, the petrol engine fires up to generate additional energy for the electric motor to consume. In these circumstances, usually brief, the powertrain turns series hybrid, the clutch open to separate the petrol engine from the electric-drive motor, allowing it to act as a generator.

At higher speeds the clutch closes to yoke the 1.4 engine and the electric motor together, their combined outputs limited to 161bhp. The 40bhp generator provides an extra accelerative boost at low speeds, besides being driven by the petrol engine to recharge the battery.

But while this propulsion strategy sounds – and is – complex, driving the TwinDrive Leon is easy. There’s the momentarily disconcerting EV experience of twisting the ignition key to hear silence, the Leon advancing on amperes, but the automatic transmission lever is entirely conventional, selection of ‘D’ allowing an immediate departure. Pull it back a notch further and you get Sport, or you can sink a green button for electric drive only, perhaps for zero emission city travel.

For many commuters the Leon will rarely use its petrol engine what with that 32-mile range, the battery best charged overnight from the mains.

Driven gently, the Seat is much like any other electric car, advancing in eerily brisk and restful silence. Accelerate hard and you can hear the petrol motor kicking in, though in the same slightly disconcerting style as an engine harnessed to a CVT transmission, the revolutions of its crankshaft bearing little relation to those of the driven wheels. But a prototype is what this car is and Seat is about to trial five examples with Spanish fleets to get an idea of how the car will be used, and what drivers think of it.

Should I buy one?

Of course, the Leon TwinDrive initiative is part of a much wider programme across the VW Group, and while the Spanish brand is making concrete contributions with this modest fleet programme and various activities with suppliers, the main driver of the project is VW. Seat’s strategic role is to make this technology more affordable to buyers. And that’s quite some challenge, Seat’s R and D chief Dr Matthias Rabe revealing that a TwinDrive Leon costs around five times as much to make as the conventional version. Closing that cost gap is one reason why we won’t be buying a TwinPower Seat, or VW, much before 2015.

Seat Leon TwinDrive Ecomotive

Price: TBA; Top speed: 106mph; 0-62mph: 11.0sec; Economy: 166.2mpg combined; Co2: 39g/km; Kerbweight: 1680kg; Engine: four-cylinder in-line, 1390cc; Installation: transverse, fwd; Power: 159bhp combined; Torque: 442lb ft e-motor, 184lb ft generator; Gearbox: single speed; Range: 32 miles electric, 550 miles combined

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skierpage 30 November 2011

powertrain details

Yours is the best explanation of TwinDrive I've seen, thanks. But there's one part that's confusing.

Autocar wrote:
When the Leon starts, it sets off electrically. But if hard acceleration is required at low speeds, the petrol engine fires up to generate additional energy for the electric motor to consume. In these circumstances, usually brief, the powertrain turns series hybrid, the clutch open to separate the petrol engine from the electric-drive motor, allowing it to act as a generator.

Surely the clutch is already open when you pull away all-electric and the motor is doing nothing. Then when the engine fires up, it must be connected to a generator to make electricity. So there must be a separate generator on the engine side of the clutch in addition to the motor driving the wheels.

Also, when At higher speeds the clutch closes to yoke the 1.4 engine and the electric motor together , the engine RPM has to match the road speed since there's no mention of a conventional gearbox. VW will have to pick some highway speed and optimize the engine for that.

Toyota's HSD e-CVT, and the Ford PowerSplit and GM Voltec variations, still seems the best way to blend electric and engine propulsion to the same axle.

audiolab 11 November 2011

Re: Seat Leon TwinDrive

Yes its complicated, but if the answer was a simple one we would all be driving it now.

It delivers sensible performance, stunning and possibly achievable economy, no range issues. Almost got it licked I'd say. Just reliability is the only question mark over it, but then again just look at how complicated normal engines are now. Maybe when the batteries die you can take them out and run it as a petrol auto!!

ronmcdonald 11 November 2011

Re: Seat Leon TwinDrive

Smurf Yeah wrote:

Perhaps I am just from a generation that is used to a much faster changing world, I love new technology I find it interesting and love to see things progress.

I agree with you. The problem is how practical? Will Seat find a way to make the technology affordable?

Remember that only a few years ago VW heralded their combined supercharger and turbo engine as the way to go... and it did go, straight to the bucket. I think I'm correct in saying VW only produce one version of that engine now (in UK at least). It was far too costly / complicated to be practical.

No doubt they'll gain technological advancements from this experiment but if it does ever come to market in 2015, I certainly won't be at the front of the queue. New technology is great, but I prefer to be paid rather than pay to play guinea pig.