THE Volkswagen Passat is becoming part of the plug-in car club with the development of a petrol-electric hybrid that is quite extraordinary.

Think that an overall 80mpg is possible in real world conditions and you will not be far off the mark with the new Passat GTE.

It will be arriving in the New Year and is set to become the most economical full-sized family car on the market.

The partially-electric Passat is the second plug-in hybrid vehicle from VW and follows on from the introduction of the Golf GTE last year.

It works by mating a 1.4-litre petrol engine to an electric motor which runs off batteries that can be charged either on the move or from the mains supply.

The main difference between a plug-in and a regular hybrid is the distance it can travel purely on electricity - up to 31 miles in the case of the Passat GTE.

That is enough for most people to complete their daily commute without having to consume any petrol, a potential saving of hundreds of pounds per year.

But unlike pure electric vehicles, when the battery power runs low the plug-in automatically switches into a more conventional mode running off the petrol engine.

The theoretical range of the Passat GTE is close on 700 miles which is the equivalent of around 65 to the gallon.

However, fuel consumption is something of a moveable feast in the world of plug-in vehicles and depends on a variety of factors.

Officially the Passat GTE is rated at 166mpg with emissions of just 39g/km but that says as much about the relevance of the current fuel testing regime used in Europe as it does about the potential of the new Passat.

On 50 mile loops over the Dutch flat lands around Amsterdam the Passat GTE showed its mettle in a number of eye-opening ways.

Through towns and villages in light traffic it actually increased its range by 25 miles such is the benefit of the hybrid system

Take in some motorways and the 50 mile journey reduced the overall range by only 20 miles and the further travelled the more advantageous it gets.

At the end of one run the average fuel readout in the car was showing an incredible 83mpg and that was leaving the car to its own devices to manage the power flow automatically.

The lowest figure we achieved was 59 to the gallon which was on the loop which included high speed motorway work.

Driving a plug-in is an entirely new take on motoring and with the Passat GTE the car can either be left in its automatic hybrid mode or switched into a variety of settings to run purely on electricity or to recharge the batteries on the move.

The battery power can also be ‘locked away' to enable the car to travel hundreds of miles normally then become an EV in the city - a congestion charge beater if ever there was.

If ultra low emission motoring is going to be a governing factor in the way we travel then hybrids like this are the way ahead.

VW has yet to finalise pricing for the GTE but after the £5,000 government grant for such vehicles the plug-in Passat is likely to cost from around £33,000 for the saloon and £35,000 for the estate - similar to the current bi-turbo diesel range topper.

In many ways the GTE is an outstanding car and it drives beautifully with good performance.

With the 1.4-litre turbo engine boosted to 156ps and the electric motor adding more power the combined output is 218ps - more than that of the Golf GTE - and there is plenty to go at.

Top speed is 140mph and the 0 to 60 acceleration time is 7.4 seconds for the saloon (slightly slower for the estate). In electric mode it can manage more than 80mph and the power delivery is instantaneous making it brisk off the mark if needed.

The six-speed semi-automatic DSG gearbox has been specially configured to cope with the hybrid system and get the best from the powertrain. Under low loads it can decouple the drive to maximise economy and that's on top of a stop/start system to help save fuel in traffic.

Fitting the plug-in system into the Passat has increased its weight by almost 20 per cent to some 1.7 tonnes but nevertheless it feels nicely robust and is very rewarding to drive.

The batteries have been slung below the car in such a way that there is no impact on cargo space which remains at a substantial 586 litres for the saloon and a minimum of 650 litres for the estate.

Recharging the cells to full capacity from a domestic supply takes just over four hours or can be done in around two-and-a-half hours from a wall mounted charging point. The connector point on the vehicle is housed conveniently behind the front grille.

Standard equipment is akin to that of any top grade Passat and the sat nav system has been modified to show the car's range limits as an EV.

There are also changes to the instrumentation with the rev counter being replaced by a power meter while outside the GTE is finished with blue trim highlights to emphasise its low emission status.

This is a very user-friendly approach to cutting edge technology - a blend of new and conventional that makes the Passat GTE simply outstanding.