Car Features

HK Engineering’s 300SL addiction


HK Engineering is the only company worldwide that is dedicated to the restoration and maintenance of Mercedes-Benz 300 SL cars. It also sells other makes of collectible cars.



One of our Historic Vehicle supporters recently visited the HK Engineering establishment in Polling, Germany and spent a most enjoyable couple of days. In addition to the expected Mercedes-Benz 300SL models on display was some interesting classic and curiosity vehicles.

HK Engineering company is regarded as a pioneer in the modern restoration business, with exceptional expertise in the 300SL. The ‘HK’ in HK Engineering, Hans Kleissl, is internationally regarded as an admirer of the Gullwing’s excellence, from its very beginning.



In addition to restoration and historic car sales, Kleissl has run his own racing department since 1995 and many Mercedes-Benz 300 SLs were prepared for historic racing in this department. These were then successfully raced in Europe and in the USA.



For more than 30 years Hans Kleissl has dedicated himself to the upkeep of historic cultural assets: in the automotive sector, centred around the Mercedes-Benz 300 SL and in the reconstruction and restoration of historic buildings, including the Polling Monastery with its old brickyard (Alten Ziegelei) and the Arendsee castle in Brandenburg.



Hans Kleissl has received many accolades for his dedication. In London, in 2014, he received the World’s Best Restoration Company award. A few years later he was awarded the Federal Medal for Monument Protection for the restoration of the the Arendsee castle. Most recently, he received the Bavarian State Office for Monument Protection (Landesamt für Denkmalpflege) 2021 award for the restoration of the Old Brickyard in Polling (Alte Ziegelei).



The restoration process



Every HK restoration project begins with an extremely detailed examination of all of the individual parts that are labeled, categorised, modularly sorted and stored.

Adhering to the company’s philosophy, as few parts as possible are exchanged or renewed. Rather, great importance is attached to restoring parts belonging to the car as faithfully as possible and then reinstalling them. Every car, thus, keeps its original identity.



Before work begins, a detailed restoration plan is drawn up, discussed and agreed with the customer. This plan is used to manage and carry out the many, individual work steps with the highest level of quality and efficiency. This careful, experienced panning makes it possible for HK to carry out a complex restoration process in a comparably tight timeframe.



The Mercedes-Benz 300 SL Coupé and Roadster body construction department processes and finishes all sheet-metal parts with exceptional precision. This high level of finish on steel and aluminum sheets depends on the use of forms and moulds developed by HK. 

These forms mean that filling and welding can be kept to a minimum, so that perfect surfaces and clearances can be achieved. The use of precision frame gauges for Roadster and Coupé space frames guarantee that tubular frames with hidden accident damage are restored to original factory specifications.



There are now five master mechanics working exclusively on engines, using state of the art engine repair machinery that allows all engine rebuilding work to be carried out in-house. HK-Engineering has had its own injection pump test bench, where pumps and nozzles are overhauled.

Top quality interiors are stitched in HK’s in-house saddlery that employs the best crafts people in their respective fields. Original materials of the highest quality ensure perfect results in both leather and carpet work.



Perfect paint and finish are ensured by professional paint preparation work, with particular attention to panel fit and blemish-free surfaces. Recently, HK has been carrying out paintwork in Nitro, using the same material that was originally applied to the majority of 300 SLs.



In the case of axles, transmissions, differentials, suspensions and brake systems the aim is, as far as possible, to restore the vehicle’s status to the original one. However, targeted improvement measures from the HK development department can also be incorporated to improve the brake system, cooling efficiency, clutch grip and power outputs.

Over recent years HK Engineering has extended its sales offering to include classic cars of other makes. Our Historic Vehicles’ visitors snapped these examples during a walking tour of the premises:



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