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).
Comparison of speedometer and mileage recording accuracy between American cars and Rolls Royce vehicles.
| Identifier | ExFiles\Box 59\2\ Scan051 | |
| Date | 14th August 1930 | |
| Hs{Lord Ernest Hives - Chair}/RmB/AD14.8.30 contd. -2- At the same time as we carried out this test we checked a number of speedometers on various American cars all of which had the characteristic that the mileage was correct to within 1 or 2% plus but the M.P.H. had an error which increased with speed, being in the worst case 17% fast at 60 M.P.H. and on an average at least 7% fast at 60 M.P.H. We therefore consider that though the R.R. mileage recording might with advantage be made 2% lower, we are certainly not reading any too fast in M.P.H. and in fact have a bare margin to ensure that we are not actually slow. HS{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} | ||