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 showing comparative cooling tests between a Rolls Royce 40/50 and a Hispano Suiza vehicle at an average speed of 35 mph.
| Identifier | ExFiles\Box 24\4\ Scan201 | |
| Date | 26th August 1924 | |
| COMPARATIVE COOLING TESTS ROLLS ROYCE & HISPANO SUIZA. AVERAGE SPEED 35 M.P.H. RADIATOR TEMPERATURES °C MILES RR 40/50 STANDARD Outward Trip "" "" NO BONNET Return Trip HISPANO SUIZA STANDARD Outward Trip "" "" NO BONNET Return Trip R.{Sir Henry Royce} Bolton 26-8-24. | ||