At Volkswagen, TDI refers to diesel vehicles with direct injection and turbo charging. TDI engines are characterised by high levels of tractive power (torque) and and very good performance yield. TDI is a registered trademark of Volkswagen AG in many countries.

How it works:
a turbocharger supplies the engine with fresh air, ensuring optimum filling of the cylinder. After compression, the diesel fuel is then directly injected into this using a nozzle at a very high pressure. Effective engine encapsulation also enables quiet operation.

See also:
Direct injection

Image of the TDI label on Volkswagen diesel vehicles

Test cycle 

The legislator prescribes standardised test procedures for the type testing of new vehicles. The procedures measure exhaust emissions, consumption and CO2 emissions, as well as the range with electric vehicles. In the past, this was done in the EU on the basis of the New European Driving Cycle (NEDC). The latter was superseded in September 2018 by the WLTP (Worldwide Harmonized Light Vehicles Test Procedure). The WLTP is intended to provide customers with more realistic current consumption values and ranges. The new test cycle is considerably longer and the test procedure is significantly more complex than the previous one.


TGI refers to the combination of a standard natural gas drive with innovative TSI technology used to directly inject petrol into turbo-charged petrol engines.
The bi- and quasi-monovalent TGI engines run on natural gas and petrol. To exhaust the full potential of natural gas as a fuel, various measures are taken to modify the engines and adapt them to suit running on natural gas.

3. Fuel consumption Polo GTI natural gas (CNG), kg/100 km: urban 4.4-4.1 / extra-urban 2.9-2.7 / combined 3.4-3.2; CO₂ emissions combined (natural gas (CNG)), g/km: 93-88; efficiency class: A+

Schematic diagram in the VW Polo with TGI natural gas mode

Tilting and sliding panoramic sunroof 

The tilting and sliding panoramic sunroof is an enhancement of the panoramic sliding roof. The roof opening system consists of at least two glass elements.

The front glass section has an electric lift and slide function. It can be tilted or opened fully. When the sunroof is slid open, the front element covers the rear element completely. The rear glass element is fixed and does not open.

The tilting and sliding panoramic sunroof has an electric roller shade that covers the entire roof.

Image of vehicle roof with tilting and sliding panoramic sunroof in the VW Passat


Torque is the force applied to a centre of rotation under a lever arm (torque = force x lever arm). The physical unit of torque is the newton metre (Nm). Modern engines should provide the highest possible torque at the lower end of the engine speed scale and the ‘widest’ possible engine speed range. An example of this is the progression of the torque of the 1.4 litre Twincharger engine: a high torque at low engine speeds (250 Nm at 1,500 1/min) and constant up to the high engine speed ranges (up to 4,500 1/min). This indicates powerful traction when starting and overtaking and lots of driving fun.

Torsen differential 

The Torsen differential is a component of the 4MOTION all-wheel drive. It is a mechanically self-locking centre differential that controls the force between the front and the rear axle depending on requirements.

See also:

Schematic diagram of Torsen differential as component of the 4MOTION all-wheel drive in the VW Touareg

Torsion beam rear axle 

The torsion beam rear axle is the most economically efficient non-driven rear axle design. Two trailing arms are connected by a transverse beam that also acts as a stabiliser. The advantages of this design are the good lateral guidance on corners and a compact spatial requirement that enables economical use of space in the rear.

See also:
MacPherson axle
MacPherson suspension strut
Double wishbone axle
Semi-trailing arm axle
Multi-link rear axle
Four-link front axle
Trapezium link rear axle

Towbar, swivelling  

The swivelling towbar can be swivelled out electrically or manually, depending on the vehicle. It is released using a switch or handle in the vehicle interior. Once released, the towbar must always be swivelled back in manually. When folded in, the towbar disappears entirely beneath the vehicle.

VW Golf, towbar detail

Traction Control System (TCS)  

For high-torque engines, the Traction Control System offers more comfort and safety, particularly on roads with differing degrees of gripping and slipping. The Traction Control System enables harmonious starting and acceleration processes across the entire speed scale without spinning wheels or lateral offset.
The Traction Control System works with the electro