After the war there were again ultra light cars both with flat twin and Vee twin engines on the market, these were more advanced than the pre-war offerings. But by the mid 1920’s they were eclipsed by the four cylinder ultra light cars that were to revolutionise the small car scene.The Rover 8,  with an 998cc air-cooled horizontal opposed twin cylinder engine, was one of the former, and as fitted with light roadster body, was a handy car. Another was the Wolseley 7hp, one of the best of the type, fitted with a water-cooled flat twin engine of 938cc. The Jowett was again on offer, continuing to evolve, at first fitted with the 815cc engine but later to be enlarged to 907cc. 1924 Jowett.
The Stoneleigh 9hp of 1922, made by Armstrong-Siddeley the aero engine makers and normally builders of quality cars of distinction, was a very basic car with an odd three seat body, with driver sat centrally and the two passengers sat behind, fitted with an air-cooled V twin 998cc ohv.designed by Hotchkiss of Coventry for BSA which also fitted it  in 1075cc form in the Ten, The Stoneleigh had coil ignition,a three speed and  reverse gearbox, a spiral bevel differential-less final drive, quarter elliptic springs all round, disc wheels and narrow section tyres. The starter was only an optional extra before 1924. With an aluminium body on a wood frame. Only 200 were made as by 1922 standards it was very crude.  The BSA Ten mentioned above, was made from 1921to1925 only in 2-seater form, In grey or blue, costing  £230, between four and five thousand were made in that time. BSA Ten .
The Ariel Nine, was another twin cylinder car made between 1922 and 1925.  In Czechoslovakia in 1922 Hans Ledwinka designed the Tatra II. It had a horizontally opposed air cooled twin cylinder engine similar to the British cars, but there the similarity ended as the gearbox in unit  was bolted to the front of a backbone chassis and the final drive to the rear and the drive taken to the back wheels by swing axles, this in conjunction with beam axle front suspension produced a revolutionary concept for it’s time and was contrary to design trends in the rest of the industry.  The design of the light cars of the post-war period, with a few exceptions, soon conformed to a  general specification that became the standard for the next twenty years, or in the case of Ford, the next thirty years. This consisted of a front mounted, water-cooled side valve, in-line four cylinder engine, a plate clutch and a three speed and reverse gearbox in unit with the engine, with a propeller shaft to a live axle at the rear. With a braced channel section steel frame and semi or quarter- elliptic springing, a beam axle at the front and four wheel drum brakes.This was the format that the designers of the new ultra light cars used, and it proved so successful that by the middle of the 20’s the simpler twins had mostly disappeared. Peugeot in France had produced the Babe before the war on similar lines, but with it’s unusual transmission. Now named the Quadrilette,  and fitted with a 694cc, later 855cc engine it was again available in 1921. Peugeot Quadrilette.
The following year other French manufacturers entered the field, Andre Citroen with his 5c.v. and the Renault 6c.v. This was soon followed by Austin in England with the Seven and  also in 1922 and the Humber 8-18hp of 1923. As the decade progressed others produced new cars, some to become famous, others to be in time forgotten. The Citroen 5c.v.  had a  maximum speed of 38mph, and 80,00 were sold by 1926. Fitted with a  water-cooled by thermal-siphon, side valve four in line engine, of 856cc, with coil ignition, a three speed and reverse gearbox, a spiral bevel final drive and with quarter-elliptic springs all round attached  to a channel section chassis frame. Michelin disc wheels were standard,with low pressure tyres in 1924. The weight of the car was 952 pounds and it was priced in England in 1922 at £195. The Renault 6CV. of 1922 had a four cylinder inline 951cc side valve engine that produced 15 bhp. water-cooled by thermal-siphon with a detachable head, HT magneto and starting by Dynomotor,Also a three speed and  reverse gear box , spiral bevel final drive, Springing was by two half- elliptic springs at the front,one transverse at rear. weighting 1512 pounds, and a maximum speed of 45 mph. Front wheels brakes by cable after 1925. It was conventional car of the period, with a feature of all Renaults at that time, the radiator was behind the engine. It was made until 1929.
The Austin Seven was a major milestone in the history of low cost motoring and set the standard for other small cars to meet for the next ten years, remaining in production in Great Britain for seventeen years. It was also made in Germany under licence by Dixi, the company later taken over by BMW. Dixi.
Licence production also took place in France by Roengart and By Austin America in the USA, although this venture by Herbert Austin  the founder and chief engineer of the company was not a success. After a disappointing period commercially after the first world war, due the cars on offer, Herbert Austin against the advice of colleagues designed  the Seven at home, to be offered as a  substitute for the Motor cycle combinations and cyclecars then available to the public. It was as compact as a combination and as light at 7 cwt as a cyclecar but with all the technical features of a full size car including four wheel braking, electric lighting and starting . Initially there were concerns weather the four cylinder high speed engine would be reliable and it’s small size usable, but the public soon  took to the car which over the years evolved with minor improvements to keeps it competitive finally going out of production in 1939. When production started in 1923 a Seven cost £225 but by 1930 was down to £125, inline with other small cars. Capable of 50 mph and 50 miles to the gallon, and able to carry four people in some models, it proved to be a very economic, reliable, durable car that also lent itself to tuning and introducing a new section of the population to sporting motoring, but that’s another story. Introduced in the same year as the Austin Seven, the Humber 8-18 h.p. with a982cc side valve engine was well made, but  twice the price of the Austin, being more a light car than a ultra light car. Other light cars of the period with a four cylinder side valve engine were the Ariel Ten of 1924, which had the gearbox in unit with the rear axle and only two wheel brakes, as did the Nine from the same stable. Ariel Ten.

The Clyno Nine of 1927, with a 950cc engine and a simpler specification and the 832cc Triumph Super Seven  which was unusual for an ultra light car in 1927, in having hydraulic brakes and balloon tyres. As well as these side valve cars there were more advanced and more expensive cars on the market, The Talbot-Darracq Of 1922, designed by L. Coatalen, with a high-efficiency overhead valve four cylinder engine of 970cc, In a elaborately equipped chassis. The Riley 9 of 1926 also had an advanced  overhead valve 1087cc engine, using two high camshafts and was built to a high standard, the Nine forming the basis for Riley touring and sports cars for the next ten years .  The Fiat 509 had a overhead camshaft engine of 998cc, more of which were to be introduced in this size of car in the next few years. The Rhode 9.5hp made in Britain from 1921 to1924, used a single overhead camshaft engine made by themselves, driving through Wrigley gearboxes, with at first differential-less back axles. Another British car with the same engine configuration was the 848cc  Singer “Junior”  of 1926. Singer used a single overhead camshaft layout in it’s engine until taken over by the Rootes Group. Morris Minor.
 The first version of the Morris Minor  of 1928, also had an overhead camshaft engine,a four cylinder version of the unit used in the Wolesley Hornet, Wolseley by then part of the Morris empire. Although the engines of these cars were advanced, the remainder of their specifications reflected the current conventions of the day. It was William Morris’s answer to the Austin Seven and although thirty nine thousand were made during the life of this model, it didn’t prove as popular as the simpler Seven. Initially fitted with cable brake operation, by 1932 a hydraulic system was fitted. The word conventional could not be used for the next subject, revolutionary would be a more appropriate , With a water cooled two cylinder two stroke engine, in unit with the three speed gearbox and final drive all transversely mounted, driving the front wheels through universally jointed half shafts, the DKW F1-500  owed nothing to convention and was years ahead of it’s time. The 584cc engine produced 16½ bhp at 3500 rpm, enough to attain a speed of 50 mph and fuel consumption of 50 mpg. Not everything about the DKW was advanced, The wood and fabric full four-seat body  was quite large and heavy and the car weighed 14½ cwt over double the weight of the Austin Seven.Citreon Cloverleaf.
Despite the introduction of more advanced engines, the side valve engine was still widely used and would continued to be in general use until the late forties. The Humber 9-28 of 1929 used a side valve engine and the rest of the car also followed the conventions of the day, as did the La Licorne 5CV  from France. During the 1920’s the ultra-light car had become establish, providing both reliable and durable transport at a reasonable cost, bringing motoring to an ever increasing section of the community. As production increased using mass production methods the cost of car ownership continued to fall, this reached an all time low in the next decade.
 

Link to the rest of Motoring For the Masses
Mainly For Fun Part two. Roaring Twenties. 1920-1930.
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