Jaguar history -1931-1936 The SS Cars
Up until 1931, the production of the company had been custom built bodies on a number of readily available chassis from other manufacturers. The result was a car that was thought more unique than the original product. Chassis used included those from manufacturers such as Austin, Wolseley, Standard, Morris and Fiat. Swallow cars were generally sporty looking, but the problem was that their looks were not backed up by performance from the chassis and engines used.  William Lyons wanted a way to gain more control over his finished product, and, in 1931 was able to reach agreement with the Standard Motor Company to produce and sell to him a modified chassis with the Standard 6 cylinder engine, This was to be the basis for Lyons first total design, which was the car that came to be called the SS. Considerable modifications were made to the Standard 16 chassis, including 3 inches extra wheelbase, and moving the engine back in the chassis. The SS1, and its smaller 4 cylinder sibling, the SS2 were introduced to the public at the 1931 Motor Show. The SS2 was based on a smaller engined Standard chassis - the 9, similarly modified to Lyons requirements.
What did SS stand for?  The simple answer is that no-one really seems to know. No reference material has been found which definititively answers the question. However ther are lots of words starting with S that could have been in Lyon's mind. Sports, Standard, Swallow, etc..
The SS1 and SS2 The SS cars were a sensation. The larger SS1 model was available as a coupe and a two door sedan, and  had long hoods, low rooflines, wire wheels and a high standard level of equipment. They looked much more expensive than they really were, establishing a tradition which Jaguar maintained for many years.
SS Cars Ltd The name of the company was changed yet again in 1933, this time to SS Cars Ltd. Lyons became Managing Director. The following year, when he wanted to take the company public, his partner William Walmesley did not agree, and amicably let Lyons buy him out,  leaving Lyons in sole charge. The SS1 was redesigned for the 1933 model year with a 7 inch longer wheelbase, and an even lower roofline.  Its looks improved considerably, as the earlier models "cycle" fenders were replaced by a flowing fender line from front to rear, which also doubled as a running board. Variations on the theme were introduced, including "two- light" and "four- light" models, a drop head tourer, and the pretty Airline coupe.  The SS2 followed suite, with a four-light saloon and a four seat tourer model. 
The SS90 and SS100 The first sports car, the SS90 was introduced in 1935, and was soon followed by a more powerful SS100. Lyons was very aware of the prestige that competiton bought to a marque, and the SS90 was conceived as a low volume sports car to fulfill this role. Based on the contemporary SS1, it was built on a shortened SS1 chassis, and featured the larger 2663cc Standard engine. The SS90 had a very short production span - just 1935 when 23 were built, before it was replaced by the SS100. The 100 featured a redesigned overhead valve cylinder head and twin SU caruburettors, which increased power from 70bhp of the SS90 to 104bhp. The cylinder head was the work of a man whose name was to become familiar with Jaguar - Harry Weslake, who was working for Lyons as a consultant at this time. The appearance of the 100 was a development of the SS90, with much larger period headlamps, and an inclined fue tank with attached  spare wheel at the rear, whereas the 90's spare wheel was mounted almost vertically.

Another name that was to become very familar at Jaguar was William Heynes who joined the company as chief engineer in 1935.

The SS100 was produced from 1935 (October) to 1939. In 1937 a larger capacity engine of 3485cc capacity was made available, though the 2.5 liter version was sold concurrently. This engine produced an output of 125bhp. The SS100 technically belongs in the next section, as it was also known as the SS Jaguar "100"
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