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).
Weight comparison table for various configurations of the 20/25 Frame and J.3 Frame.
| Identifier | ExFiles\Box 107\4\ scan0125 | |
| Date | 5th January 1934 guessed | |
| 20/25 Frame. J.3 Frame. Complete Car 4200 lbs. 4060 lbs. Chassis 2860 lbs. 2900 lbs (estimated) Chassis with 20/25 Engine 2985 lbs. Chassis + 20/25 Engine + Vulture Box 2875 lbs. 3000 lbs. Car + 20/25 Engine + Vulture Box 4160 lbs. Above Car + Vulture Body 4460 lbs. | ||