Volvo Penta 's new D6-310 marine diesel engine has been honoured with the Editor's Choice Award by the American magazine Motor Boating . The new generation D6-310 and D4-210 engines, displacing 5.5 and 3.7 litres respectively, were launched by Volvo Penta last autumn and are being installed in boats in the 22ft to 45ft size range. Volvo Penta has increased production capacity at its Vara, Sweden engine plant to meet demand for the new engines.