I have recently bought an PV544 ( 1964).
There is a big problem with fuel Consumption.
What would be the causes?
(recently It was tunned Up)

 

Nice car!
Sorry but not familiar at all with this particular engine, but you could check the obvious first, like a dirty fuel/air filters, too low pressured tires, etc.,

 

have the carbs been serviced? what do the plugs look like and are they the correct temp and gap? I suspect the engine is running rich. Another thing to check is the compression - rings may be getting tired. Any oil consumption? Also who did the tune up? Did they set timing and the points gap correctly?