The Wurzburg Residence was designed in 1720, commissioned in 1744 and added to Unesco's World Heritage List in 1981. This masterpiece in south German baroque is a delight in the clear morning sun as we pit stop from the autobahn drive in Audi's new A3 Sportback. It's not the Sportback we're used to in Hong Kong, but the new two-litre TDI version that is still unavailable here, perhaps thanks to our government's aversion to diesels. Even so, we're testing the car to keep up to date with the latest diesel technology that most of the world seems quite happy with. We will also find out whether the TDI Sportback will help you make the most of a cheaper euro for jaunts across Europe. And who can blame you for revving your engine when Audi says the 170-horsepower A3 Sportback 2.0 TDI can almost cover 1,000km on a 55-litre tank. We're about two hours from Munich airport, but we're not in a hurry. If we had to race down to Rome to catch a flight at the same time it would be much more fun. But we put the Sportback through its paces, as you might on holiday, on a mix of motorway and country roads in Baden-Wurttemberg and Bavaria. We pass through tiny towns with small walled cities dating back to the Middle Ages, including Rothenburg, Dinkelsbuhl and Nordlingen, where the Audi thrives on beautifully surfaced roads amid breathtaking scenery. The Sportback's slightly extended boot is packed with luggage and camera equipment, yet it rarely notices. The six-speed S tronic dual-clutch automatic gearbox is clearly designed to return good fuel economy and seems to hit sixth from a standstill in no time. Audi's latest turbo direct injection engine offers an impressive 350Nm of torque from 1,750 to 2,500rpm. The maximum output of 170hp peaks at 4,200rpm, a figure not too far behind the 180hp achieved by the highly successful 1.8T model. With its long gears, it is very relaxing in village-to-village and in-town driving. It is old news in Europe diesel engines are a consistent choice in various market segments, except for one or two cities I can think of where sense never plays a role in the decision to flaunt one's wealth. And the diesel block unit in the Audi 2.0 TDI shows how out of the loop Hong Kong drivers can be about diesels. Its predecessor was the world's most frequently built diesel engine, according to Audi. But it was not available in Hong Kong, thanks to some bogus regulation. Given the prowess of the previous unit, the 2.0's performance is perhaps unsurprising. The unit is powerful, fuel-efficient and clean. Audi's Ingolstadt engineers have made just one major change inside the newly developed inline four-cylinder engine, using a common-rail system in place of the previous unit's injectors. The new engine has an extremely fine fuel atomisation and efficient combustion system made possible by a new 1800 bar injection system. That means better fuel economy and a quieter drive. The noise and vibration in the cockpit nevertheless suggest the Sportback might not have the most refined diesel block in the world, but its emissions are low, thanks to a particulate filter. One diesel engineer says we'll never see black smoke coming out of exhaust pipes again. It is beyond my knowledge why diesel-powered passenger cars are not encouraged for private use in Hong Kong, given the improvements most European carmakers have made since the 1990s. Perhaps our Environmental Protection or Transport departments could explain the reasons to motorists, or maybe our Customs and Excise Department or Financial Secretary know better. In Germany, a litre of diesel fuel is about 3 per cent cheaper than a litre of petrol. But it's the efficiency of diesel engines that wins buyers. A diesel often gives 20 per cent more mileage on the same quantity of fuel used by a comparable petrol engine, as is the case with Audi's 2.0 TDI and 2.0 TFSI. Diesel engines seem to work more efficiently with added torque in situations when it matters most, such as accelerating from traffic lights, overtaking and low-rev cruising. We clock 280km to Munich airport in a run involving many detours. When we hand back the car we learn we have consumed 17.6 litres of diesel fuel - 6.3 litres per 100km and not far from the combined fuel-use figure of 5.6 litres provided by Audi. If we hadn't stopped over in all those places, I'm beginning to think the Audi Sportback could have gone to Rome on a tank of fuel after all. The A3 TDI would be a fun drive and a fine advertisement for its diesel technology in China, so perhaps Audi might consider shipping a few test cars to Hong Kong while we wait for local government officials and motor traders to explain why there aren't more diesel cars on our roads. Gary Tsang is the former editor-in-chief of the Post's magazine Automobile and the China representative in the International Engine of the Year Awards AT A GLANCE: Audi A3 Sportback 2.0 TDI What drives it? A 1,968cc, 170-horsepower, in-line, four-cylinder TDI direct injection diesel engine with VTG turbocharger linked to a six-speed dual-clutch automatic box driving the front wheels. How fast is it? Audi says the three-door version with the same drivetrain reaches 100km/h in 7.8 seconds and has a top speed of 222km/h. No figures are available for the five-door Sportback. How safe is it? It has xenon headlights, a tyre pressure monitoring system, a dynamic stability control system, driver and front-passenger front and side airbags and side airbags for rear passengers. How thirsty is it? The three-door version is said to consume 5.6 litres of diesel per 100km on a combined cycle. No figures are available for the Sportback. How clean is it? The three-door blows 148 grams of CO2 per kilometre, the equivalent of 1.2 Smart ForTwos.