[2] A supplementary air supply controlled by a foot pedal operated at will by the driver provides an oil mist from inside the engine's crankcase to lubricate the tops of the valve sleeves.

A three-plunger pump driven by the valve shaft forces oil from the sump to troughs under and in the path of the big ends.

The propeller shaft is fully enclosed and has a ball and fork joint at its forward end.

During acceleration there is a low periodic noise as of escaping steam which disappears once under way and the car runs silently.

There is a very powerful clutch stop which requires a gear change to be made in one rapid movement.

[3] The new Rover 12 was first displayed at the November 1911 Olympia Motor Show as a 4-cylinder supplement to the 2-cylinder sleeve valve cars.

It had a four-cylinder, water-cooled, side-valve engine of 2297 cc with an SU carburettor made by Rover under licence.

[7] Spencer Wilks was given almost a free hand to make improvements from the time he began his work at Rover.

Thomas's design was effectively a 10/25 engine with two more cylinders though dimensions differed to make it fit within the desired tax rating.

[10] Rover's new car was announced 21 August 1931 described in advertisements as: a 12-horsepower six-cylinder having a four-speed gearbox with a silent third gear, capable of 65 to 70 mph and 28 to 30 miles per gallon[11] A de luxe model included safety glass in all windows.

[8] "The engine exerts its power with an air so modest as to be deceptive" declared Autocar in its report timed to match the release of the Pilot.

[12] In February 1932 "following a reorganisation of the company's management"[note 1] Rover announced strengthening of the Pilot and Family Ten chassis by using heavier gauge material and re-designed cross members to improve torsional rigidity.

These improvements were, they said, the outcome of lengthy testing on New Zealand's and Australia's roughest roads carried out to make the cars suitable for overseas use.

The crankcase had been enlarged to provide a larger oil capacity, compression ratio lifted and petrol was now supplied from a new rear tank by Autovac.

[9] Special plant was installed at Rover's works to spray the inside of all body panels with asbestos to ensure quietness fire-proofing etc.

[9] Also in July 1932 the Pilot received the wholly new chassis of the Ten Special, its flexible engine mountings,[10] Startix and the new gearbox and freewheel.

[16] Twelve months later a subsequent road test reported that fresh modifications allowed the engine a more spontaneous response.

The suspension was conventional with rigid axles and half elliptic leaf springs all round.

An updated version appeared in 1937 with mainly styling changes but the chassis was stiffened and Girling rod brakes replaced the hydraulic ones that had been fitted to earlier cars.

[21] There were no more tourers pre war but 200 were made in 1947 and 1948[22] with the first four bodies by Rover and the remaining 196 by AP Coachbuilders of Coventry.

The 1938 models had fixed bonnet sides and for 1939 synchromesh was added to the top two ratios on the gearbox.

[24] The final cars were made in 1948 and there was no real replacements as subsequent models featured larger engines.