From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The actual maximum speed of the 20-MY model and speedometer accuracy.
| Identifier | ExFiles\Box 18\4\ Scan027 | |
| Date | 13th April 1933 | |
| X7960 S/W. Hs.{Lord Ernest Hives - Chair}(c to Wcr) Cx{Major Len W. Cox - Advertising Manager}18/KW13.4.33. re- Speed of 20-MY Thanks for your Hs{Lord Ernest Hives - Chair}3/KT12.4.33. Of course the conditions would have to be very favourable, i.e. wind behind and a down grade, to get the high speeds referred to by Kaye Don. I do not know what is the error of the speedometer on the car in question, but I have twice personally had the speedometer needle on the 100 mark. Admittedly the conditions were very favourable. I often wonder what people really mean when they refer to the maximum speed of a car. Whether it is the maximum speed on dead level in a still atmosphere against the watch, or whether it means the maximum speed that could be obtained on a car irrespective of conditions, in other words, the speed at which the engine will turn over before the power falls away and the speed peak has been reached. I suppose that with the speedometer needle on the 100 mark on 20-MY, allowing for 4-5% error in favour of the car, it is actually travelling over the road at about 95 m.p.h., so I suppose one would be justified in saying that the car could actually do 95, provided that remark is qualified by the words under favourable circumstances. True we are rather guarded here how we use that statement, as people are often apt to forget about the favourable circumstances and would expect to do it on the level any time even forgetting, as they sometimes do, the direction of the wind. Cx.{Major Len W. Cox - Advertising Manager} duly | ||