Lower CO2 emissions anyone?

Ever since the passenger car diesel tax was reduced in July 2008, Audi and Volkswagen have been testing the diesel car market here by introducing several diesel-powered models ranging from super minis to a sporty coupe and big SUVs.

One of the cars that we've previously test driven on oneshift is the Audi A5 3.0 TDI quattro. When it comes to diesels, nobody does it sexier than Audi. The Four Rings might have introduced the cleanest and most fuel efficient four-seat passenger with the A2 1.2 TDI back in 2001 but it is in 2006 that the brand put the words disel and racing side by side by creating history by winning the Le Mans 24 hours endurance race with the diesel powered R10 TDI prototype sports car. The A5 TDI is not only stylish but it goes rather well too as I found out when I drove it previously. Key to the A5 TDI's strong and impressive performance is a smooth operating 3-litre V6 turbodiesel churning out 240bhp and more impressively, 500Nm of twisting force. With so much torque on hand, the A5 TDI was a breeze to drive on both the open highway and in traffic. The bent six is exceptionally refined as well as there's hardly any diesel clatter at idle or low speeds. The diesel engine is such a sweet and efficient performer that the 3.0 TDI quattro can well be the best A5 variant out there after the RS 5. To further emphasise the A5 TDI's fuel sipping nature, oneshift's contributing photographer, Yang took the car up to Sepang and back on a single tank of fuel last year. And Yang is not known to be a light footed driver!

I recently experienced another of Audi's modelson sale here powered by the widely used 3.0 TDI lump for a weekend - the Q7 3.0 TDI. In a big SUV weighing 2.2 tonnes, the 240bhp oil burning V6 was in its own element, offering the 550Nm pulling power needed to haul the Q7 up to speed from standstill. In terms of torque output, the diesel offers 110Nm more than the 4.2 FSI model. The TDI's slower 0-100km/h time of 8.2 seconds is 8 tenths off the 4.2's pace but this figure isn't exactly represnetative of its flexible and tractable grunt.

While there are obvious benefits in terms of pulling power, engine flexibility and fuel consumption (the TDI betters the 4.2 FSI by 2.3km for every litre of fuel) With the TDI, there's only a small trade off when it comes to refinement - you can feel some minor vibration through the pedals in the TDI but there's none of the noisy diesel clatter from older diesel models. A diesel motor in a big SUV like the Q7 somehow makes even more sense than in a stylish coupe.

Another interesting diesel car that I recently experienced was the 2-litre Volkswagen Golf GTD. The GTD is basically a GTI with a 2-litre TDI lump rather than a TSI. This said TDI lump is based on the ubiquitious VAG 2.0 TDI found in Seat, Skoda, Audi as well as VW models like the Tiguan and Passat among others. The versatile four-cylinder unit is tuned for more power - 170bhp versus the 140bhp one in most other models while torque output of 350Nm is even more than the Golf R's highly tuned 330Nm.

On the road, the GTD offers more instant get-up-and-go performance that is unmatched by the GTI. With the narrower rev band of a diesel, obviously one might miss the power or a high revving engine once in a while, especially on a race track or a stretch of open highway but our congested city streets proved that the GTD's low end diesel grunt is even more exploitable than the GTI's petrol power. Moreover, the GTD delivers its go while making a nice sounding growl that is worthy of a pure hot hatch. The handling dynamics are similar to the GTI's, including the responsive steering and tight suspension. The GTD offers all this fun while returning an average fuel consumption figure of 5.6 litres per 100km. The annual road tax based on the current system on the other hand is over three grand - ouch!

Credits: Story by Raymond Lai Photos by manufacturer and Raymond Lai