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Gas consumption

The car runs fine but all of a sudden I am only getting about 4 mpg. There are no visible gas leaks and go gas smell. Any suggestions as to what i should check?

Please give the year, milage, and recent history of the car to help the guys here figure out a possible diagnosis.

It is a 1998 that has 114,000 miles. Everything seems to be fine. This is a new issue that seems to have come from nowhere.

leaky gas tank? It is a metal or composite tank?

tank is metal. Does not appear to have a leak any where. No drips and no gas smell.

Have you lost some engine power, particularly at high speeds?
Is the check engine light on?
Has the check engine light ever flashed? Has the O/D off light ever flashed?
Is maintenance up to date? (For example, when were the spark plugs last changed?)
Any smoke out of the exhaust?
How are you determining the MPGs?

do you have a locking gas cap? does someone you dont trust have a key to it? could your gas be getting siphoned in these hard times by a night crawling thief?

Still have good power. check engine light is not on. engine light nor O/D have flashed. No smoke from exhaust. I am not sure of last spark plug change. Oil and filters are changed regularly. I only drive this car to work and back. I am determining milage based on distance traveled per tank of gas.

I would install a locking gas cap and double check the fuel lines for leaks. Your truck is old enough to have rusted through the fuel lines. To get 4 mpg, the fuel has to be leaving somewhere. I don’t think the engine can use that much fuel and still run, especially without symptoms.

I heard mileage was bad, but that seems really bad. Regular maintenance, air filter gas filter, spark plugs etc. up to date? No warning lights?

I’m having a very hard time seeing a vehicle like this getting 4 MPG while apparently running fine, emitting no smoke, and no CEL to boot.

Thieves in the night or whatever but it does not sound like an engine performance fault.