Volvo has extended downward the engine range for its new S40 and V50 compact models (launched in 2003) with the addition of 1.6-liter engines in both gasoline and diesel versions. The 1.6-liter diesel delivers an average fuel consumption of 4.9 liters/100 km (48 mpg US) and is the most fuel-efficient engine ever offered by Volvo Cars.

The inline-4, 1.6-liter diesel engine is a turbocharged unit with variable turbo geometry. Both the cylinder block and head are of aluminium to minimize weight and fuel consumption.  The new diesel develops a maximum output of 81 kW (110 bhp) and a torque of 240 Nm, providing acceleration from 0 to 100 km/h in 12 seconds (0-60 mph in 11.4 seconds).

The new gasoline engine is a four-cylinder, 1.6-liter, normally aspirated unit. The engine output is 74 kW (100 bhp) and the torque 150 Nm.

The side-by-side comparison of the two highlights the capabilities of the diesel engine: a slightly smaller, more efficient engine, with lower fuel consumption and lower CO₂ emissions delivers acceleration only 0.1 second slower than its gasoline cousin...and that ranks worse on emissions.

Volvo offers an optional self-cleaning particle filter to reduce PM emissions further, but I do not have information on the amount of the reduction—or what impact it might have on performance.

As part of the Ford-PSA cooperative agreement on engineering and producing diesels, Volvo Engine in Sweden is gearing up to produce the 4-cylinder, 2.0-liter diesel already offered in the S40 and V50.

The introduction of the smaller (downsized) engines is in keeping with a spate of similar announcements from other automakers seeking to lower emissions of CO₂ for the European fleets in keeping with the Kyoto guidelines.