Why Drive a TDI?
You'll enjoy the savings. Economical fuel consumption, long service and maintenance intervals, plus low emissions, all combine to keep costs low.
You'll love the drive. Our turbodiesel engines offer exceptional torque even at low revs. This results in tremendous fun at the wheel, thanks to their effortless acceleration and sparkling performance.
You'll feel the power. High levels of pulling power over a wide rev range offer real driving pleasure.
How does it work?
Fuel needs oxygen to burn and the engine has to be supplied with huge quantities of air to get enough. You can solve this problem with a bigger engine - or you can solve it with a turbocharger - as in the TDI. Driven by the exhaust gases, it squeezes air more tightly into the cylinders.
The air is then cooled (cool air takes up less space than hot air) and diesel injected directly into the cylinders at very high pressure through a nozzle. It's this intensive mixing of highly atomised fuel with the compressed air that leads to better, more efficient combustion.
Your driving experience is quiet and refined because effective sound insulation keeps noise to a minimum, while hydraulic engine mounts ensure smooth, low-vibration running.
What's the result?
The great advantage of TDI engines is that they are very powerful, even at low revs, and economical across the entire speed range. As they burn fuel more efficiently they produce more power. What it means for you is much better performance, with more pulling power than you would get from traditional fuel injection systems. This efficiency also means that you save on fuel costs and emit less CO2, so helping to minimise your impact on the environment.
Overcoming turbo lag
The main disadvantage of a turbocharger is that it needs a certain gas pressure to work, only available when engine revs are high enough. To avoid 'turbo lag' a delay in available power - and be very efficient at lower engine revs, the turbocharger needs to be able to control the exhaust pressure.
A variable turbine geometry (VTG) turbocharger does this with a system of mechanical guide vanes. It alters the cross-section of the exhaust flow inlet on the powertrain side. If the gas pressure falls at slower engine revs, the control system adjusts the guide vanes to narrow the cross-section. This speeds up the exhaust flow and increases the pressure. And as the exhaust gas pressure rises with the engine revs, the control system makes the inlet cross-section larger by altering the position of the guide vanes.
Volkswagen injection systems
We are one of the leaders in developing advanced efficient diesel engines with lower emissions. Our innovative unit injector engines are progressively meeting the new EURO 5 standard, ahead of legislation. Our range of three to ten-cylinder turbodiesels is based on unit injector systems, or common rail injection.
How injection works
The pressure at which the diesel is injected into the cylinder is the key factor in diesel direct injection. The fuel has to mix swiftly with the compressed air in the cylinder. The higher the pressure, the more finely the diesel is atomised for an intensive mixing of the fuel and air particles. This, in turn, leads to better and more efficient fuel burning. The energy from the fuel is used more effectively and emissions are reduced.
We use various injection stages within one power stroke - referred to as multiple injection. Depending on the engine design, revs and load, modern diesel engines use a pilot or double pilot injection, a main injection and a post injection. Pilot injection achieves smooth combustion, ensuring that the extremely high pressures necessary for combustion to take place are reached more gradually. This significantly reduces combustion noise and cuts emissions. Post injection helps the combustion process further, achieving even lower exhaust emissions.
Piezo crystal injectors
To control the injection process precisely and cut fuel consumption and emissions significantly, we use piezo inline injectors instead of solenoid valves. They are lighter and respond twice as fast. This enables the injector valve to switch five times faster to meter the fuel and control the injection curve far more precisely. It's an important factor in achieving efficient and smooth combustion with low emissions.
Compared with previous systems, diesel injection with piezo injectors offers the potential, depending on the design, to reduce fuel consumption by roughly three per cent, to lower emissions by up to 20 per cent, to increase the achievable engine power by up to five percent and to approximately halve engine noise.
Common rail - third-generation diesel direct injection.
Common rail is the cutting edge of diesel technology and will eventually replace all our TDI engines. The common rail system stores the injection pressure in a high-pressure fuel reservoir referred to as the 'common rail' as it supplies all the injectors. In this system the generation of pressure and the fuel injection processes are separate.
Lines connect all the cylinder injectors to the common rail in parallel, ensuring they all have an uninterrupted supply of constant pressure.
The advantage of common rail is that fuel can be delivered at higher pressure, giving better mixing with air for a more efficient and cleaner combustion. This gives you higher performance combined with improved fuel consumption.
The ever-higher injection pressures that make diesel engines cleaner and more efficient than before place big demands on the common rail system. Our latest generation of diesel engines reach injection pressures as high as 1,800 bar. For this reason we make the rail ourselves, and we are the first car maker to do so.
The diesel particulate filter
Our advanced diesel engines are much cleaner than older engines. One important factor is their diesel particulate filters (DPF), which are very effective in cutting emissions, trapping even the finest soot particles that are produced as the engine burns diesel fuel.
The latest generation of filters operate without additives. This makes them maintenance-free for an exceptionally long time: an initial inspection is usually carried out only after 150,000 km. The filter's lifespan is dependent on factors such as fuel quality, driving style, use and oil consumption.
What the heck is BlueMotion anyways?
BlueMotion isn't just a single technology. It's a whole range of innovations and refinements that help you save fuel and money, without taking the fun out of driving.
BlueMotion Technologies represent the cleanest, most energy-efficient cars in our range. So when you see this logo you'll know we're talking about ways to cut your emissions and driving costs.
Our BlueMotion Technologies are designed to lessen the impact of driving on the environment. The BlueMotion badge already identifies the cleanest, most eco-friendly cars in our range: now we're extending it to cover all our innovative energy saving and fuel efficient technologies, such as the DSG dual-clutch gearbox and TSI and TDI engines. Other examples of BlueMotionTechnologies include recuperation of energy from braking, advanced aerodynamics, optimised gear ratios, low rolling resistance tyres and the start-stop system. They all work together to make our cars more economical and to reduce emissions.
The foundation technologies
Efficiency starts at the very core of our cars with their engines and gear boxes. Innovative technologies such as TSI, TDI and DSG are major contributors to driving efficiency and set a solid foundation to develop from. They play an important part in keeping Volkswagen at the forefront of economical engineering.
Advanced engines such as the powerful TSI and the high-torque diesel TDI, ensure outstanding fuel consumption and fewer pollutants together with pure driving pleasure. The impressive DSG Dual-Clutch gearbox offers even greater fuel economy. It has the convenience of an automatic gearbox and the agility, dynamic performance and superior consumption figures of a manual gearbox. So being efficient doesn't have to take the fun out of driving.
The innovations
Our engineers have developed a series of innovations specially geared towards conserving energy and reducing fuel costs without compromising your driving pleasure.
We've created modified engine management software that makes our engines run even more efficiently. We've also been able to reduce the engine idle speed so you emit less C02 and use less fuel. Our BlueMotion gearboxes have been reconfigured with longer ratios in higher gears for the most economical fuel consumption. Intelligent technology tells you when to change gear for optimum driving efficiency.
The innovative start/stop system turns the engine off when you're idling in traffic and restarts it when you're ready to move while the recuperation mechanism uses some energy usually lost during braking and deceleration to pass additional charge to the battery. The outside of this range is equally as crafted as the inside: from the low rolling resistant tyres which reduce road friction to the specifically designed aerodynamic styling, BlueMotion means less fuel consumption, lower emissions and a better driving experience.
BlueMotion Technology cars...
Our efficiency technologies have been implemented across a range of cars, making them more economical. You'll recognise these cars by the BlueMotion Technologies badge they carry. So when you see this logo, you're looking at one of the cleanest, most energy-efficient cars in our range.
BlueMotioncars...
BlueMotion cars are our most efficient cars yet. They offer the ultimate in economy as well as producing the lowest C02 emissions. These cars are expertly designed with aerodynamic styling kits and include all our BlueMotion Technologies, delivering superior performance. The BlueMotion range includes the Polo, Golf and Passat.