While tuning for the best fuel mileage a vehicle is capable of is a protracted and time intensive process of returning everything from the ground-up as far as possible to how the manufacturer would like it to be, the consumption of your car is so great it should be patently obvious where the fuel is going...
Assuming it isn't being leaked away which should be obvious and should be the first check made - getting underneath while the engine is running and checking with a good light, a good spark proof light... If it isn't being leaked away the fuel must be being consumed by the engine and in this case the engine wouldn't sound right, wouldn't smell right and wouldn't run right, in fact, using several times more fuel than it should, it should be difficult to start, misfiring due to sooted or wet spark plug(s) and producing black exhaust smoke and/or flammable vapour.
Depending where that fuel is going, your car could be potentially dangerous to be around it and you need the urgent assistance of an expert. It could have an injector stuck open, for instance...
Answers & Comments
While tuning for the best fuel mileage a vehicle is capable of is a protracted and time intensive process of returning everything from the ground-up as far as possible to how the manufacturer would like it to be, the consumption of your car is so great it should be patently obvious where the fuel is going...
Assuming it isn't being leaked away which should be obvious and should be the first check made - getting underneath while the engine is running and checking with a good light, a good spark proof light...
If it isn't being leaked away the fuel must be being consumed by the engine and in this case the engine wouldn't sound right, wouldn't smell right and wouldn't run right, in fact, using several times more fuel than it should, it should be difficult to start, misfiring due to sooted or wet spark plug(s) and producing black exhaust smoke and/or flammable vapour.
Depending where that fuel is going, your car could be potentially dangerous to be around it and you need the urgent assistance of an expert. It could have an injector stuck open, for instance...
You have either a leak in the fuel system, need a rebuilt carb, have brakes that are not releasing or a badly slipping transmission.