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Green with envy

Volvo cars are known for their safety and sympathetic ecological stance. It is therefore of no surprise that the Swedish success story should invest even further in its clean diesel technology in the form of the brand new D5.

The rise of popularity of diesel in Europe isn't new news. It seems that some carmakers like Mercedes-Benz are so confident with diesel that they are even risking introducing it to the sceptical US market. The German carmaker has just announced that it aims to regain its place as the top importer of this often misunderstood gas to the US, a position it held from the 1960s to the 1980s.

Volvo doesn't have such plans as yet. A spokesman from the Swedish carmaker admits that it makes sense, but that the company doesn’t have the same resources as DaimlerChrysler to risk loss across the Atlantic.

In Europe, though, diesels have long lost their tainted reputation as being the dirty and smelly poor cousin to petrol. Last year, petrol powered cars were overtaken by diesel cars on Europe’s roads, at least in the sales statistics. Exactly 110 years after Rudolf Diesel launched his groundbreaking invention, the proportion of diesel-powered cars in Europe has exceeded 50 per cent for the first time ever.

Volvo is currently one of the most fast-growing participants on the diesel market. When production of the first in-house developed diesel engine started in 2001, the proportion of diesel engines in the company's European sales figures was just over 20 per cent. Just four years later, Volvo has passed the 50 per cent mark.

The next step is to further boost the competitiveness with the introduction of a new, more powerful and cleaner generation of five cylinder turbodiesel engines. The Swede's cylinder diesel range now includes three engines, with power outputs spanning from 128 to 188 ps (94-138 kW) and with torque between 300 and 400 Nm (221 and 295 lb ft).

"We cover most customers’ requirements by increasing the number of horsepower. Only 16 per cent of buyers want a diesel engine with more than 186 ps (138 kW)," says Gerry Keaney, senior vice president sales, marketing at Volvo.

"Highly effective particulate filters, one of the cornerstones in our system upgrade, give the diesel engine additional environmental benefits," explains Keaney. "What is more, diesel engines are becoming increasingly dynamic and more comfortable. That is why the diesel engine's market share is set to increase still further in Europe." He even predicts that it is likely for 70 per cent of all new cars in Europe to be powered by diesel in 2010.

The diesel market share varies considerably between different markets. The market is topped by Austria, Belgium, France and Luxemburg, who already belong to 70 per cent. Spain, Italy, Portugal and Germany are all between 60 and 40 per cent. The UK is on the upswing and, despite a high price for diesel fuel at the pumps, has crossed the 30 per cent mark, while the proportion of diesel-powered cars is still below 10 per cent in Greece and Sweden.

The new generation of in-house manufactured five cylinder diesel engines will initially be available in the Volvo's S60, V70, XC70 and XC90. And driving these cars is blatant proof of how far the fuel has come.

"With our most powerful turbodiesel has been spiced up with another 22 ps (16 kW), rising from 165 to 188 ps (121 to 138 kW), we become even more competitive in all the segments," says Keaney. "The S60 becomes far sportier; the V70 and XC70 also get a huge boost in power and for the XC90, diesel becomes a far more attractive choice."

When it comes to the S60 most of the diesel buyers in the segment want an engine between 132 and 172 ps (97 and 127 kW). In the segment with V70 and XC70 last year's diesel volume peaked between 172 and 181 ps (127 and 133 kW). The XC90 also covers the most popular diesel choices, between 162 and 171 ps (119 and 126 kW).

The first generation of the in-house developed diesel engines were fitted in over 305,000 Volvo cars since its introduction. The company's target for the new generation diesel engines is to double that figure during the next four years, to as many as 600,000 units.

In 2006, Volvo expects to sell 85,000 units of the new five cylinder diesels. Production of the new generation of turbodiesels started at Volvo's engine factory in Skovde, Sweden in mid-May this year. Initially, the focus is on building cars with manual gearboxes. The production of cars with automatic transmission starts in early October 2005.

Green and lean

Volvo's five cylinder diesel engine, which was first introduced in 2001, has been extensively improved and refined. This has resulted in an entirely new driving experience with considerably higher performance, and improved drivability. At the same time, there has been a sharp reduction in emissions.

The new engine is actually three different ones, all of which are turbocharged. The most powerful version, the D5, has been given an extra 22 hp and has a maximum output of 188 ps (137 kW). The increase provides excellent high-speed performance, with fast acceleration and efficient pulling power, even when driving up long, steep hills, with no need to change down.

Torque has also increased dramatically, from 340 to 400 Nm (250 and 295 lb ft). This provides extra power and considerably quicker response at both high and low rpm.

"We have improved nearly everything in the engine," says Jörgen Svensson, chief programme engineer. "The driver will perceive it as a lively petrol engine, only more powerful and more environmentally efficient."

Most of the increase in performance can be attributed to an upgraded air and exhaust gas exchange system, a new turbocharger, and an improved injection system. Most of the air and exhaust channels have been given increased volume and more gentle bends for more efficient gas-flow with low losses.

The new generation turbocharger has electronic control, resulting in fast and precise control of the charge pressure. A larger compressor wheel provides higher torque and output. Furthermore, the variable vanes have been cambered for a more efficient flow of gas at all settings, resulting in an increased level of turbo efficiency. The improvements contribute to both faster acceleration and better high-speed performance.

The turbo centre housing is now water-cooled, which is unusual in diesel engines. This is caused by the higher performance of the new engine and provides continued cooling of the turbo after the engine has been switched off. This is particularly beneficial during short stops after high-speed driving, such as when refuelling on the highway.

As was the case on the previous diesel powertrain, air swirls in the cylinders' combustion chambers. The use of a new electronically controlled multi-throttle system in the inlet ports allows for infinitely variable regulation of the swirl level, and combustion can be adjusted extremely accurately according to the driving situation and the current engine speed and load.

"We have also made the combustion chambers larger, thereby lowering compression," notes Svensson. "By doing so, we have gained two things: higher performance and lower emissions."

The injection system has been fitted with new injectors with seven finer nozzle openings as opposed to five in the previous engine. This results in a more finely atomized fuel mixture, and more efficient combustion. Injection takes place in three steps: pre-injection, primary injection, and post-injection. The last step is new and contributes not only to cleaner combustion but also to regeneration of the particulate filter.

A completely new, electronically regulated quick glow system results in considerably reduced glow times, also making it easier to start the engine in cold weather.

The new diesel engine has very low emissions, thanks to a number of new and refined functions. For example, emissions of nitrogen oxides (NOx) have been halved. A new-generation engine management system, with increased capacity and a greater number of sensors offers more accurate control of the engine’s functions. This includes electronic control of the throttle and the new, more powerful Exhaust Gas Recirculation (EGR) valve for more precise regulation of the air supply and recirculation of exhaust gases.

"We also have a completely new EGR cooler," says Svensson. "This lowers the combustion temperature very efficiently, thereby reducing emissions."

The catalytic converter is now fitted close to the engine, not just on manual but also on automatic versions, to promote faster warming and thus faster start-up of the exhaust cleaning process. The catalytic converter is also larger than before. In addition it has been supplemented with an oxygen sensor that precisely regulates the fuel mixture and emissions.

All versions of the new diesel engine have a particulate filter as standard equipment. It very effectively removes soot particulates from the exhaust gases, with filtration efficiency above 95 per cent. The filter is a Coated Diesel Particulate Filter (CDPF), in which a special coating helps burn the particulates. Therefore, no additives are needed, and the filter requires no maintenance. Burning away soot particulates takes approximately 20 minutes and occurs automatically at 500 to 1000 km intervals, depending on driving conditions.

Three musketeers

The new diesel engine is available in three versions, all with the same cylinder volume and common technology:

Engine Output ps/kW Torque Drive
D5 188/137 (previously 163/120) 400 Nm (previously 340) AWD/FWD
2.4D 165/121 (previously 130/96) 340 Nm (previously 280) FWD
D 127/94 (previously 116/85) 300 Nm (previously 280) FWD

In addition to the technical changes, the diesel engines' service interval has been extended from 20,000 till 30,000 km.

The improved All Wheel Drive (AWD) system with Instant Traction, which was introduced on the XC90 V8, can now be combined with other XC90 engines. The system will also become available for four-wheel driven S60, S80, V70 and XC70s. Instant Traction makes starting easier on slippery surfaces by immediately distributing the right amount of power to the rear wheels the instant the car starts to move.

"The D5 engine with a six-speed gearbox and AWD is a nearly unbeatable combination," says Svensson. "It offers enormous driving pleasure while also providing power and low-rpm capacity for the most demanding uses."

In short, most of the measures taken on the new diesel engine result in both an increase in performance and reduced emissions.