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).
Consumption test comparing overdrive and normal top gear performance.
| Identifier | ExFiles\Box 147\5\ scan0124 | |
| Date | 25th February 1937 | |
| 1249. To Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls} from Rm{William Robotham - Chief Engineer}/GR{George Ratcliffe} Rm{William Robotham - Chief Engineer}/GR{George Ratcliffe}6/M.25.2.37. 37 EX. Consumption test with overdrive. OVERDRIVE. 190 MILES/42.2 MPH/10.8/MPG. NORMAL TOP. 190 MILES/38 MPH/11MPG. Rm{William Robotham - Chief Engineer}/GR{George Ratcliffe}, | ||