The 4.5 used exclusively for the American market beginning in 1972 is known for its lousy gas mileage.....around 14 mpg on average.
I suppose its a combination of things like lower compression (8:1 vs the preceding 3.5s 9.5:1), less than ideal camshaft and ignition timing, use of a torque converter transmission instead of the more efficient (but rougher) hydramatic style torus coupling and the inherent poor aerodynamics of the W108/109 body design.
But STILL.....
Any tips on how to improve on this? Without spending 20 years worth of potential gas money savings on extensive modifications?

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Berfinroy in CT
Present vehicles:
1973 300 SEL 4.5
1959 Rolls Royce Silver Cloud I
1959 Ford Thunderbird convertible/430
Past vehicles;
1958 Bentley S 1
1976 ex-Max Hoffman 6.9
1970 300SEL 2.8
1958 Jaguar MK IX
1961 Jaguar MK IX
1963 Jaguar E-type factory special roadster
1948 Plymouth woody
1955 Morgan plus 4
1966 Shelby GT350H Mustang