The Opel 1.8-litre is a luxury car manufactured by Adam Opel AG. Production commenced in January 1931, and continued till November 1933. The Opel 1.8-litre was the first new Opel to be launched following the purchase of an 80% share in Opel by General Motors (GM), and the first Opel to have been designed and developed by GM in North America .
The 1.8-litre has been seen as a replacement for the Opel 4/40 which had gone out of the production in September 1930, although in terms of advertised performance the new model was less powerful and, as launched, a little slower than the older car as well as being approximately 300 kg lighter.
The car came with a 1790 cc six cylinder side-valve engine fed by a Solex 30FV carburettor. A maximum output of 32 PS (24 kW; 32 hp) at 3,200 rpm was claimed. Advertised top speed was 85 km/h (53 mph). Power was transmitted to the rear wheels using a three speed gearbox controlled with a transmission stick beside the driver, in the middle of the floor.
1933 saw a small increase in both the compression ratio and the claimed power output. The transmission was replaced with a four speed unit, but still without synchromesh. This was now the transmission that would be fitted in the Opel »6« 2-litre when it appeared the next year. The claimed top speed now increased to 90 km/h (56 mph).
When production started in January 1931 with the so-called Opel 1.8-litre Series 18B, there were essentially three different body options. The entry level model was a two seater cabriolet with fixed side windows and a fold-out “Dickey-seat” at the back, aggressively priced at 3,175 Marks. There was a four door Limousine (sedan/saloon), and there was also a two door “Sonnen-Coupe”. The “Sonnen-Coupe” had a black imitation leather roof covering, which the casual observer might mistake for a folding roof, and which curiously adumbrated the vinyl roof coverings which became fashionable among several mainstream auto-makers and their customers in Europe in the 1970s. The “Sonnen-Coupe” was in fact a style already familiar in France where cars with this type of body were called “Faux-Cabriolets” (False cabriolets). An added twist with the Opel 1.8 Litre “Sonnen-Coupe” was an openable steel panel sun roof, denoted by the reference in the car’s name to the sun.
Other body types that soon became available were a Torpedo style two door “Touring” body, a “Roadster” and a two door “Limousine” (sedan/saloon).
During its first year the 1.8 litre Series 18B enjoyed fantastic success in the market place, with 15,739 cars produced in a single year. In 1931 and 1932 the German auto-market was badly depressed as the economy suffered badly from the aftershocks of the 1929 stock market crashes. Opel was already Germany’s leading auto-producer, but the number of customers that the 18-litre found is particularly impressive given the total German passenger car sales figure of just 56,039 in 1931.
Towards the end of 1931 Opel introduced the 1.8 litre Series 18C, for the 1932 model year. This was little changed from the Series 18B, though the range of bodies was further broadened. On the outside the two piece bumper was replaced by a simpler single piece bumper, although cars lower down the range still came without any bumper. The manufacturer's prices for the Series 18C cars were for most bodied versions several a few hundred marks lower than for their 1931 equivalents, reflecting several years of price deflation in the German economy during the early 1930s.
July 1932 saw the introduction of a new “Regent” all-steel bodied “Limousine”. The “Regent” bodied cars had nothing in common with the ill fated Opel Regent of 1929 apart from the name. In place of the conventional vertical rear end of the earlier 1.8 litre, the “Regent" body came with a sloping rear that followed the fashion for streamlining and incorporated a luggage locker. A spare wheel was mounted on the rear panel and access to the fuel filler was through a fuel cap positioned through the hole in the middle of the spare wheel. The first “Regent” bodied 1.8-litre was a two-door saloon/sedan, but during the next few months the new fashionable “Regent” body equivalents were offered of the more conservative original bodied. The only exception was the a Torpedo bodied “Touring” version which retained the more perpendicular profile of the original Opel 1.8-litres. In addition to the “Regent” bodies 1933 also saw the introduction of a four door Series 18N “six-light” limousine.
Between January 1931 and November 1933 Opel produced 32,285 1.8-litre models. The Opel 1.8-litre was the number one seller of Germany’s largest auto producer in 1931. By 1932 it had lost the position to the manufacturer’s smaller recently introduced 1.2-litre. In 1933 the German auto-market started a sustained rebound, with 82,048 cars sold, nearly twice the level of the previous year, but most of the market growth was achieved by newly available smaller less expensive cars such as Opel’s 1.2-litre and the DKW F2. With 9,406 cars manufactured in 1933, its final production year the Opel 1.8-litre now in its third and final year achieved impressive volumes for a six cylinder car.