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 comparison between a 4¼ litre Bentley Chassis B.58 GA and a Demonstrator model, testing speedometer accuracy and acceleration.
| Identifier | ExFiles\Box 89\1\ scan0268 | |
| Date | 11th April 1939 | |
| Comparisons between existing 4¼ litre Bentley Chassis B.58 GA and Demonstrator loaned by Bentley Motors Limited. -------------------- In the first place the speedometers on the two cars were checked over a measured half mile of private road and the following results were obtained:- B.58 GA Demonstrator Speedometer reading Time Correct speed Time Correct speed 60 31.6 sec. 57 m.p.h. 32.2 sec. 56 m.p.h. 70 27.4 " 65¾ " 27.2 " 66 " 80 23.8 " 75½ " 24.2 " 74½ " 90 21 " 85¾ " 21. " 85¾ " The above figures indicate that generally speaking the speedometer on the demonstrator was more optimistic than my own and therefore the following results are really more favourable on my car. No allowance was made for this difference in the speedometer readings. B.58 GA Demonstrator Top Gear Third Gear Direct Gear 20 - 40 7 secs. 6 secs. 6.6. secs. 20 - 50 10.8 " 9.2 " 10.4 " 20 - 60 15.4 " 13.3 " 15.4 " 20 - 70 21 " 18.5 " 20.6 " A further test which I carried out was from 20 - 80, using on my own car 2nd, 3rd and top, and on the demonstrator 2nd and direct drive. 80 m.p.h. was achieved in the case of my car in 23.8 seconds, and on the demonstrator in 25.2 seconds. 11.4.39. | ||