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).
High-speed vehicle test conducted on the Autobahn, detailing performance and handling.
| Identifier | ExFiles\Box 160\3\ scan0132 | |
| Date | 30th January 1939 guessed | |
| ( 2 ) Petrol tank refilled on Autobahn with 40 litres after 406 miles on speedometer. All tyres blown up on the station to supposed 50 lbs/sq" front and 55 lbs/sq" rear. These were checked after running 1 hr. 12 mins. on the autobahn when cold at 40 lbs/sq" front and 48 lbs/sq" rear. Initial attempt finished at the end of the Autobahn beyond Karlsruhe. 15 miles recorded in 9 minutes at 100 m.p.h. average. Maximum 3800 r.p.m. at 124 MPH. Oil Temp. 130°c Return run made towards Mannheim. Maximum 3600 r.p.m. at 118 MPH. Oil Temp. 137°c Speedometer check. 20 secs for 1 Km. at 185 KPH. 116 MPH. 21.4 " " " " 179 " 112 " Large errors are 22.6 " " " " 168 " 105 " liable with hand 23.8 " " " " 160 " 100 " operated stop watch at these high speeds. Engine r.p.m. check with speedometer. 3800 at 124 m.p.h. 198 k.p.h. 3600 " 118 " 189 " 3500 " 110 " 176 " 3000 " 96 " 154 " 2500 " 80 " 128 " 2000 " 62 " 100 " At Mannheim the car was then driven towards Frankfurt and reversed at Darmstadt for return to Mannheim. This ended the running on the Autobahn having covered the first 15 miles in 9 minutes; 85 miles in the hour and 100 miles in 1 hr. 12 mins. (83 m.p.h. average). A section of the Autobahn from Karlsruhe to Stuttgart was also included in the running but was useless for test, owing to ice and snow. All stretches of the Autobahn used were only wide enough for two cars abreast, and all the running was subject to existing traffic of private cars and lorries. Traffic averaged about 62 m.p.h. - 100 k.p.h. The brakes on this car are average for the standard Bentley but are certainly not good enough for 120 m.p.h. on the Autobahn with the traffic encountered. At 120 m.p.h. when the engine is cut off, the car has a very slow deceleration even with the r.p.m. increased from 3,800 to 4,300 by changing down to direct gear from the overdrive. | ||