The four digits of the identification numbers are composed of two sets of two digits: two for the price range the model is in, and two for the model number. I.e. model number 11 in price range 13 would be 1311. Sieper Werke uses the following price ranges based on production costs (‘Club Series’ are not discussed here!):

08 - Convertibles or Cabriolets
10 - Regular passenger cars
13 - Cars with plastic accessories (police cars etc.) and small vans
14 - Cars with special print
16 - Small vans with plastic accessories, ambulances and small trucks
17 - Small truck, tractors and forklifts
19 - Medium vans, cars with trailers
20 - Large vans
22 - Larger models with trailers, small excavators
25/26 - loaders, medium size trucks, small trucks with trailers
28/29 - medium size trucks, military equipment
31 - Trucks with trailers or semi-trailers, medium excavators
34/35 - Trucks with heavy load, heavy excavators, airport fire engines
37/38 - Heavy trucks with accessories
39 - Heavy trucks with other models on trailers (cranes, excavators etc.)
40 - Heavy trucks with multiple plastic accessories
41 - Large metal cranes

Sieper Werke decided to change the scale of their models from 1:60 to 1:55 to incorporate more details. The first models in the new series were old ‘V series’ casts, which received a new identification number. All new casts were in 1:55 scale, in which they still are today with the exception of the ‘Club Series’ models introduced in 1990 and marketed as ‘Super Series’ since 1993.

But the scale was not the only thing that changed; Siku models became more and more recognizable due to the new plastic wheels with white 5-spoke and later wire print and the new box types they came in. Also the company introduced their first official trademarked logo: the Siku name in a white disc surrounded by three colored rings. The first passenger cars were offered in cardboard boxes, while the larger models like vans and trucks were packaged in cardboard boxes with clear plastic windows. By 1979 all the passenger car models were packaged in the blister packages which are still in use today.

In 1986 part of the Ludenscheid factory was rebuilt, as a result of a large fire, and updated with the latest technology. All the models were still produced here until 1990 when the ‘Club Series’ of 75mm models were introduced. The production of the ‘Club Series’ as well as the passenger cars in the ‘Super Series’ was gradually moved to the new Hong Kong based factory. All the larger models are still produced in Ludenscheid, Germany. Sieper Werke is still owned by the Sieper family and has been a family business since the 1920’s.

Sieper Werke used their philosophy "Kids want to play with what their parents drive" in the ‘Super Series’ and produced many popular German cars like the VW Beetle, Golf, Passat and Transporter, the Opel Kadett and Senator, the Porsche 911 and 928 and many Mercedes Benz models. Besides these German hits there were also some less popular cars done like the Lamborghini Espada 400 GT and the Alfa Romeo Montreal. And for those interested in heavy material there is also wide variety of trucks, tractors and excavation equipment available (their Faun heavy crane is still in production after 24 years!).

As far as variations go there are various window colors in the models of the 80’s. The print on the wheels is either the early 5-spoke print (white or silver) or the later wire print (white). Both are known in several width sizes. In 1990 all the wheel types were replaced with the new alloy-style ones which have two variations: regular or Mercedes Benz. The trucks also switched from print to alloy-style plastic and are outfitted with rubber tires since 1999.

A rare variation is the Porsche 911 Turbo Siku produced as an answer the color changing Hot Wheels. This model is bright orange when cold and pink when warm. Although Sieper Werke never actually took this model into production the ones they dumped somehow found their way to collectors.

Collectors should be able to gather almost all of the ‘Super Series’ cars in mint condition at prices ranging from $ 2 for models in production up to $ 40 for mint obsolete models. The larger trucks can cost up to $ 75.