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).
Table comparing dynamometer ratios for Humber, Dodge, and Hupmobile cars.
| Identifier | ExFiles\Box 21\5\ Scan014 | |
| Date | 24th May 1921 guessed | |
| X4213 AMERICAN CARS. Dynamometer Ratios. X 1525 X 4213 X 4212 Revs. | Humber. | Dodge. | Dyn: Revs. Hupmobile. ---|---|---|--- 500 | 74 | 79 | 67 750 | 111 | 118.8 | 101 1000 | 148 | 158 | 135 1250 | 185 | 198 | 168 1500 | 222 | 237 | 202 1650 | 259 | 277 | 236 2000 | 296 | 316.8 | 270 | ||