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).
Graph comparing Miles Per Gallon (M.P.G.) against Miles Per Hour (M.P.H.) for an Overland 4 Coupe.
| Identifier | ExFiles\Box 75\2\ scan0283 | |
| Date | 1st February 1922 | |
| M-P-H M-P-G RE-AT. M.P.H | WITH | WITHOUT 11 | 2.25 | 3.25- 15 | 3.00 | 3.75- 20 | 3.50 | 4.25- 25 | 4.50 | 6.25- 30 | 5.75- | 7.25- Best economical settings in both cases. OVERLAND 4 COUPE Note particularly the indication of an increased economical driving range when the reatouriser is fitted. oy FEB 1 '22 KEUFFEL & ESSER CO., NEW YORK, NO. 334 C. | ||