We've just driven Honda's new iDTEC diesel engine installed in the current Accord. This will go on sale as the range-topping diesel unit in the all-new Accord due next summer.It's still a 2.2-litre, but heavily modified, with improved combustion and a particulate filter. And this time round there will be two states of tune: the lower-powered one promises around 155bhp and will also have the option of an auto 'box for the first time. The meatier engine is likely to be a manual-only at launch, and you'll get 180bhp to play with. Both engines are promising more refinement and more punch than the current 140bhp motor, although an insider admitted that they are unlikely to serve up extra economy and lower emissions as the new Accord is lardier than the current one.On the move the new diesel feels like a sophisticated device. Less noise filters into the cabin than with the current diesel engine, and it settles down to become an extremely quiet cruiser, especially the lower-powered car. Both engines felt usefully punchier too, even with the smooth-shifting auto fitted; that's likely to be tempered a little by the new Accord's extra weight.Either way it's further proof that despite a late start Honda is really getting to grips with diesel. Our quick test track drive proved that its capable of matching BMW, Audi and Merc for performance and refinement. If the next year's Accord is as good as its diesel engine, it's likely to be some car.