French automobile maker PSA, responsible for the Peugeot and Citroen brands, has just sold the 50,000th example of it’s Hybrid drivetrain in Europe.
PSA launched its diesel-hybrid system at the beginning of 2012. It’s used in four different models, Citroen’s DS5 Hybrid4, Peugeot’s 3008 and 508 Hybrid4
and the Peugeot RXH, a diesel-hybrid crossover. With 167 horsepower to the front wheels and 37 bhp from the electric motor, combined power is 200 horsepower–making the diesel hybrids some of the more rapid options in their respective ranges.
The system is a dual axle-hybrid. In contrast to a traditional hybrid where the petrol/diesel engine and electric power are combined and sent through the same set of wheels, dual axle-hybrids use a different powertrain at each axle. In PSA’s case, that means a 2.0-liter turbocharged diesel engine at the front axle (with power sent through an automated manual transmission), and an electric motor setup at the back.
The benefits for drivers are mostly tax-related. Diesel engines ensure good motorway economy, while the hybrid drivetrain allows greater city mileage. This combination results in a low CO2 output–under 100 grams per kilometre, in most cases. As a result, sales as a proportion to the models they’re based on are 
high. In the Citroen DS5’s case, one in every three models sold is the hybrid.
Other companies, including Mercedes and Volvo, also offer diesel hybrid models, the latter a plug-in-hybrid capable of producing over 120mpg. But the costs of producing them are high resulting in the list price to the consumer restricting European sales.