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TDI embossed on the engine cowl
Turbocharged Direct Injection (acronym: TDI) is the technology used to describe and name modern turbocharged direct injection diesel engines produced by Volkswagen Group, and widely used in all marques of passenger cars and light commercial vehicles produced by the company (particularly those sold in Europe).

TDI is a registered trademark of Volkswagen Aktiengesellschaft.


The engine uses direct injection, where a fuel injector sprays atomised fuel directly into the main combustion chamber of each cylinder, rather than the pre-combustion chamber prevalent in older diesels which used indirect injection. The engine is coupled with a turbocharger to increase the amount of air going into the engine cylinders, and an intercooler to lower the temperature (and therefore increase the density) of the air from the turbo, thereby increasing the amount of fuel that can be injected and combusted. These, in combination, allow for greater engine performance (from a more complete combustion process compared to indirect injection), while also decreasing emissions and providing more torque than its petrol engined counterpart.

Similar technology has been used by other companies but "TDI" refers to these Volkswagen Group engines. Naturally-aspirated engines (those without a turbocharger) made by Volkswagen Group use the label Suction Diesel Injection (SDI).

The reduced material volume of the direct injection diesel engine reduces heat losses, and thereby increases engine efficiency, at the expense of increased combustion noise. A direct injection engine is also easier to start when cold, due to more efficient placing and usage of glowplugs.


The first Volkswagen Group TDI engine was an Audi-developed 2.5 litre inline five-cylinder, introduced in the Audi 100 in 1989. The TDI arrangement has been enhanced by improving the efficiency of the turbocharger, increasing the pressure at which fuel can be injected, and more precisely timing when the injection of fuel takes place. There have been a few major generations, starting with what are known as "VE" engines. In 2000, the Pumpe Düse (PD, variously translated "pump nozzle", "unit injector", "pump injector") engine began to appear in Europe, eventually coming to North America a few years later.

The PD design was a reaction to the development of common rail fuel injection by competitors - an attempt by Volkswagen Group to create an in-house technology of comparable performance that would not require any royalties to be paid. While Pumpe Düse engines had a significantly higher injection pressure than older engines, they are slightly less refined when compared to the very latest common rail, and weren't able to control injection timing as precisely (a major factor in improving emissions). New engines appearing in 2009 model year Volkswagens are using the common rail technique with piezoelectric injectors.

Motor racing

A motor racing version of the common rail TDI engine made an impact in 2006 when it was used in the Audi R10 TDI, which won the 12 Hours of Sebring and 24 Hours of Le Mansmarker, becoming the first diesel-powered car to win either of those races. Fuel economy was a significant factor, as the car did not have to refuel as often as others in the race. The car used a special synthetic diesel from Shell as fuel.

In 2007, SEAT - with the León Mk2 TDI at the Oschersleben Motorsport Arena in Germany - became the first manufacturer to win a round of the World Touring Car Championship (WTCC) series in a diesel car, only a month after announcing it will enter the FIA World Touring Car Championship with the León TDI. SEAT's success with the León TDI was continued, and resulted in winning consecutively 2008 World Touring Car Championship and 2009 World Touring Car Championship both titles (for drivers as well as for manufacturers).

Direct injection turbodiesel engines are frequent winners of various prizes in the International Engine of the Year Awards. In 1999 in particular, six out of twelve categories were won by direct injection engines: three were Volkswagen, two were BMW, and one Audi. Notably that year, the Volkswagen 1.2 L TDI 3L beat the Toyota Prius to win "Best Fuel Economy" in its class.


TDI engines run on diesel fuel (called petrodiesel in North America), or B5, B20, or B99 biodiesel subject to manufacturers' prior approval.

In fuel efficiency, and clean emissions when run on biodiesel or when converted vegetable oil (which should NOT be used on the later PD engines without prior conversion, since irreparable damage will result), TDI engines are among the best on the market. A 2007 Volkswagen Jetta 1.9 TDI with 5-speed manual, for example, achieves 5.2 L/100 km (54 mpg UK or 45 mpg US) on the European combined-cycle test, while a Direct-Shift Gearbox (DSG) automatic reaches 5.9 L/100 km (48 mpg UK or 40 mpg US).

Newer TDI engines, with higher injection pressures, are less forgiving about poor-quality fuel than their 1980s ancestors. Volkswagen's warranty does not cover damage due to bad fuel (petrol or bio), and has in the past recommended that only mixtures up to 5% biodiesel (B5) be used. Volkswagen has recently permitted mixes up to B20, and has recommended B5 be used in place of 100% petroleum-based diesel because of biodiesel's improved lubricating properties.

No. 2 diesel fuel is recommended since it has a higher cetane number than No. 1 fuel, and has lower viscosity (better ability to flow) than heavier fuel oils. Some owners in North America, where cetane levels are generally poor (as low as 40), use additives or premium diesel to get cetane numbers closer to the standard levels found in the European market (at least 51) where the engine is designed. Improved cetane reduces emissions while improving performance and may increase fuel economy.

New ultra low-sulfur petroleum-only diesel recipes cause seals to shrink and can cause fuel pump failures in TDI engines; biodiesel blends are reported to prevent that failure.


For all Volkswagen Group diesel engines Volkswagen AG requires that lubricants must meet VW505.00, 505.01, 506.00, 506.01, or 507.00 standards.

A number of brands of motor oils are now "VW Approved" to the above standards; there do exist, however, a few off brands not approved by VW that print the VW number on the label and hide in small type the word "recommended". Volkswagen AG only carries out in-house testing on motor oils to grant the necessary approvals; if Volkswagen AG, therefore, has not carried out such tests (or if a submitted oil has failed their tests), Volkswagen AG will not grant approval. Volkswagen Germany and Volkswagen of America freely publish up-to-date lists of currently approved oils on their respective websites, along with the technical resource, erWin. Volkswagen AG does not permit any independent testing facility to grant their own standards.

European models with "LongLife Servicing", "Extended Service Intervals", "ESI", or "WIV", must be run on official VW LongLife lubricants, namely 506.00 (for non-PD), 506.01 (for PD), or the very latest 507.00. Volkswagen of America, however, warranties require frequent oil changes even if ESI hardware is installed. Finally, the very latest TDIs with Diesel Particulate Filter (DPF) must ONLY use 507.00 oils.

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