Volvo’s V60 Plug-In Hybrid wagon is a runaway success. The first year’s batch of 1,000 cars sold out before any had a chance to reach showrooms, and Volvo announced in November that it would increase production to 4,000-6,000 units for model year 2014. That figure will now be raised to 10,000 units, according to Cars UK.

The British motoring mag speculated that the popularity of the ultra-fuel efficient wagon may have much to do with Europe’s many clean-vehicle incentives. In several countries, buyers pay a hefty tax on new cars, based on a model’s carbon emissions. With a figure of 48 g/km, Volvo’s PHEV can save a buyer thousands in taxes.

Local goodies for green drivers also abound. In London, cars with emissions below 75 g/km are exempt from the city’s $15-per-day congestion charge.

On the other hand, the sort who can afford to pay 50,000 quid (around $77,000) for a new car probably don’t base their decisions solely on savings. Perhaps the V60’s many fans like the performance (0-60 in 6.1 seconds) or the 4WD feature (the diesel engine powers the front wheels, and the electric motor the rear).

The winning wagon features a 2.4-liter five-cylinder turbodiesel engine. Total output is 285 hp, electric range is 31 miles, and combined fuel economy (on the lenient European cycle) is 129 mpg.

Ramping up production may be a challenge – Volvo builds the PHEV on the same production line as its other models, but had to make some modifications to the line, as the PHEV includes over 300 more parts compared to a plain old V60.

Sources: Cars UK, Green Car Reports