SEAT Leon TwinDrive

The TwinDrive provides the best of both worlds by harnessing cheap plug-in power with none of the range restrictions of a pure EV. Engine engagement is seamless, there’s plenty of power and the control system lets you use the various forms of drive when it best suits. Competitive pricing should be the icing on the cake.

The Ecomotive line-up currently accounts for 47 per cent of SEAT’s UK sales, and the firm plans to increase that with a Leon plug-in hybrid Ecomotive, due in 2015.

Called the TwinDrive, the car is one of several versions of an all-new Leon that’s due to be unveiled at March’s Geneva Motor Show. We’ve tried the technology that will underpin the new model in an existing Leon.

Video: watch CarBuyer's video review of the SEAT Leon

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Under the skin is the VW Group’s 1.4-litre TSI petrol engine linked to a 116bhp (85kW) electric motor. These either work independently of each other or combine to give a power output of 159bhp.

The lithium-ion batteries, which sit under the boot floor, are charged via a socket next to the front foglamp. As with other range-extending EVs, a full charge takes about eight hours from a domestic supply, or two hours from a high-voltage fast charger.

Turn the key and the silence tells you the TwinDrive starts every journey running solely on battery power. It’ll do 32 miles in this mode and hit a 75mph top speed. Yet push a button on the centre console, and this Leon reverts to being a regular hybrid.

It does so in such a seamless manner that you barely notice the internal-combustion engine firing up. The really clever part of the TwinDrive, though, is the control unit integrated into the sat-nav.

This lets you programme how you use plug-in power. If, say, you have a 20-mile motorway commute before 10 miles of urban driving, the car can be told to save its mains-generated power for the town section. And if you exhaust the cells, the 1.4-litre engine can always kick in to turn generator and recharge the battery. As a result, this Leon has a total range of 562 miles.

At high speeds, a clutch engages and the engine and electric motor work together to maintain momentum. On the motorway, the engine is so refined you can barely hear it, and even under hard acceleration its noise doesn’t become unpleasantly harsh.

The extra shove from the electric motor’s 600Nm of torque gives a handy turn of speed, particularly between 30mph and 50mph.

However, the car’s economy figures are its most eye-catching asset. SEAT claims it will return 166mpg, with a CO2 figure of only 39g/km. A premium of £2,500 is expected over the diesel.

On current form, that puts this Leon’s starting price at around £20,000, making this new string to SEAT’s bow a very attractive proposition indeed.