UNUSUAL TEST.

Auckland Star, Volume LXXI, Issue 191, 13 August 1940, Page 14

UNUSUAL TEST.

Motor Notes.

EFFECT OF MILEAGE. ON PETROL CONSUMPTION. Particulars are to hand from U.S.A. of an unusual motor test which' will interest most car owners. A fleet of nine 1940 model Fords, Chevrolets and Ply mouths, three of each make, were driven 1000 miles a day over *J7O-mile circuit in Florida at an average speed of 50 m.p.h. Relays of drivers, representative of the general motoring public, handled the cars in relays of eight-hour shifts. The test was conducted with a view to ascertaining the average fuel consumption of the respective vehicles after travelling 100,000 miles, as compared with similar model cars which had lieen driven only a comparatively short mileage during their "running-in*' period. The test showed that the cars, even after travelling 100,000 miles, during which they had been systematically lubricated and cared for, were giving practically the same petrol mileage as when they started on the test and were capable of attaining only two mile* an hour less top speed than the cars which had only been just "broken in." Acceleration throughout the 100,000 miles test was for all practical purposes equal to new car performance. To determine if any great loss of maximum speed had resulted, three new 1940 models, each identical with the test cars after being broken in, were respectively driven over a flying start mile on the Daytona Beach (once the venue of the world's mile motor record). The average mean speed of the new models was 79.83 m.p.h., and that of three "test" cars 77.9.1 m.p.h., a difference of less than 2 m.p.h. Electric-eye timing was used. The average petro consumption of the test cars per American gallon (onefifth less than the Imperial" gallon) was 18.5 m.p.g. at 10,000 miles, 19.1 m.p.g. at 75,000 miles and 18.9 m.p.g. at 100,000 miles. The test demonstrated that, when the cars were new, they only needed 64 octane petrol to ensure" "knock-free" performance. After being driven 10,000 miles they needed 73 octane fuel to prevent "pinking." After covering 50,000

miles, the requirement was 75 octane petrol. These results were obtained without any removal of carbon from combustion chambers. From other experimental work, it was indicated that carbon removed at 50,000 miles would be expected to reduce the octane requirement from 75" to about 70 octane. The test showed that ■ major changes in octane requirements took place under 25,000 miles. The general conclusion drawn from the exhaustive marathon test was that, with the improvements in petrol, oil and cars, the most important factor in long car life is maintenance, which means systematic and regular lubrication service and mechanical adjustment —in a word, proper upkeep.