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 of results from fuel consumption tests comparing two vehicle models with different carburettor and wheel setups.
| Identifier | ExFiles\Box 122\4\ scan0210 | |
| Date | 29th October 1938 | |
| -2- Results of consumption runs. Average Speed Tests (7 1/2 Miles at 60 M.P.H.) | 6.B.IV. | M.P.G. | 7.B.V. | M.P.G. | Notes | |------------------------------------------------------------|--------|--------------------------------------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | Standard 1" carbs. (L.B.1 needles) | 14.2 | 1 1/2" carbs with B.J.A. needles. | 13.35 | B.J.A. needles were best available at time of testing. They were just too weak for full throttle pick up 10 to 30 M.P.H. | | 1 1/2" carbs. with B.J.A. needles. | 13.8 | 1" carbs with Lbl needles. | 13.1 | Carburetters complete inter-changed between the two cars. Little change in relative petrol consumptions, but the weakness follows the carb-uretters making 6.B.IV much too weak. | | Same as previous test, but with rear wheels interchanged. | 13.8 | | 14.05 | Interchanging rear wheels gives a reversal of con-sumptions due to 1" difference in tyre size. Allowing for sligh-tly better con-sumptions due to a slower run the reversal is amost exact, giving 1/2 M.P.G. better cons. for 7.B.V. 6B.4 is very weak. | | ||