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).
Performance graph for a Vauxhall 25 HP vehicle tested at Brooklands, showing tractive resistance and horsepower required at various speeds.
| Identifier | ExFiles\Box 155\1\ scan0318 | |
| Date | 24th June 1937 | |
| AT BROOKLANDS VAUXHALL 25 HP TRACTIVE RESISTANCE CURVE HP REQUIRED AT ROAD WHEELS WEIGHT 30 CWTS 3 QRS HP MPH. SECS. TABLE: MPH. | HP 60. | 27.8 50 | 15.2 40. | 7.8 30. | 5.35 20 | 3.08 FD{Frank Dodd - Bodies} 1.7.37 | ||