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).
Fuel consumption, comparing their vehicles with American models and exploring factors like power-to-weight ratio and overdrive.
| Identifier | ExFiles\Box 147\5\ scan0127 | |
| Date | 31th May 1937 | |
| Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} [Handwritten]: 1263 .1249 Rm{William Robotham - Chief Engineer}8/R.4.6.37. CARBURATION. Sg{Arthur F. Sidgreaves - MD}9/E31.5.37. We have been taking considerable interest in petrol consumption lately. We have been using the Chevrolet for comparison. When we left America this was accepted as being as economical as any car from the consumption point of view. The Americans get very good fuel consumption because they have very light cars, and, in consequence, can use high gear ratios. We have done sufficient work to say that we know how to equal American consumptions if we put our engine in one of their cars. On the 25/30, with a curb weight of 42 cwts, and a final axle ratio of 4.6 we cannot, however, compete with an Oldsmobile or Buick having curb weights of 33 cwts and final axle ratios of 4.33. A good example in our organisation of the effect of power weight ratio and axle ratio is the Bentley, and the 25/30. With the same engine unit the Bentley does 18/19 m.p.g. and the 25/30 15/16 m.p.g. under ordinary touring conditions in England. The French tests are not representative of ordinary touring. The overdrive will do more to help our fuel consumption than any other alteration we can make. Rm.{William Robotham - Chief Engineer} | ||