Audi TT, VW Golf or Skoda Rapide - on the face of it these cars could not be more different from each another. Under the metal skin though, they are closely related and will become even more so in future.
Carmakers are keen to cut development costs and reduce the period it takes to get new models on the road. What better way than to pool resources?
"Almost all the manufacturers are currently looking at so-called platform or modular concepts, which allow them to produce a range of cars using common components," says Jan Dannenberg from Berylls strategic advisory service in Munich.
Volkswagen's system for the shared modular construction of transverse, front-engined, front-wheel drive cars is called "Modularer Querbaukasten" or MQB; in English - Modular Transverse Matrix.
The system uses a core matrix of parts and has been used to assemble the new Golf 7, says development chief Ulrich Hackenberg. It will form the basis of around 40 models in the medium term, he adds.
Future front-wheel-drive vehicles from Wolfsburg will share the same front axle and transverse engine location plus pedal box position. The wheelbase, track and external dimensions remain flexible. This means MQB models can range from the compact VW Polo to the larger Skoda Superb.
VW is not the only carmaker to rationalise production. Ford boss Alan Mulally has repeatedly announced in Detroit that he aims to reduce the number of modules the company uses worldwide from 25 to nine.
Mercedes-Benz' own version - MFA - will initially be used for the new A and B Class cars. They will be manufactured in the same factory and use identical axles and drivetrains. Mercedes hopes this will cut costs and save six months of development time per model.
There is no need to simplify cars completely in order to lower overheads and profit from the "Lego principle". Individual components can be used across a range. BMW's eight-speed automatic transmission is slotted into the top-of-the-range 7 Series as well as into the entry-level 1 Series cars. The only difference is the software configuration used for each application.
The Bavarians employ the same principle with their diesel-electric hybrid drivetrain, regardless of whether it is fitted to the 3 Series, 5 Series or 7 Series.
"This strategy enables manufacturers to offer a wide range of models quickly and produce or buy in the components at advantageous prices," says Berylls adviser Dannenberg.
The modular principle aids production and harks back to the early days of standardised mass production. "A variety of models can be assembled using a single shell or basic production line. This boosts plant flexibility and also helps lower costs."
A further benefit is that innovative driver assistance devices or infotainment systems can be incorporated into a larger number of models at less cost and in quicker succession than at present.
There is a downside to the modular approach. Construction and production blunders reverberate throughout the entire range, generating much higher costs if something goes awry.