The Laurin and Klement Mladá Boleslav car originally had a five-litre sleeve-valve engine, which 1st owner Kolowrat ordered to be replaced in the factory in 1921 by a special M type racing engine with overhead valves, of which only two were made.

It was purchased in 1913 by the famous race driver Count Alexander 'Sasha' Kolowrat and played an important role in the early days of motorsport in young Czechoslovakia. In the spring of 1921, Kolowrat asked the factory in Mladá Boleslav to replace the original sleeve-valve 5-litre RK engine with a special racing M-type OHV engine, which was built at his order in only two copies. Shortly after this upgrade, however, Kolowrat sold the car to František Svoboda, a car garage owner from Prague. In 1921 and 1922, Svoboda participated with this car in most of the then still not very numerous national car races and competitions.

In 1922, he finished in the overal first place in the race between spa towns and won in its category in hill-climb races Ecce Homo and Schöber. In both of those years, he also took part in the Czechoslovak International Reliability Trial, but the first time was disqualified for accepting outside help and the second time acquired penalty points for erroneous listing of engine capacity. Passenger car with a water-cooled four-stroke four-cylinder OHV engine placed lengthwise behind the front axle and with a rear-wheel drive. Engine displacement 4715 cc, output unknown, maximum speed 125 km/h. Producer: Laurin & Klement, a. s., Mladá Boleslav.

Top. Count Kolowrat behind the wheel of his Laurin & Klement RK car. This car still has its original sleeve-valve engine and original mudguards.

Bottom. Kolowrat's upgraded car with František Svoboda behind the wheel after completing the second Czechoslovak International Reliability Trial, which took place on 4-10 September 1922. During this 2.390 km long event, Svoboda had to repair a punctured tire nine times and due to his administrative mistake ended with 5 penalty points.