Soamer

I’ve had the car 4years and the last twelve months once filled up which normally will last around 430miles but once and a while you can go a short distance and use 1/4 of a tank in 18miles which normally would be around 110 miles engine runs fine just odd that once in 10 weeks it dose this

Many thanks first quarter is normally about 130 miles dependent on sped and road type it is odd on how it did this but tonight been on a 36 mile trip fuel gauge hadn’t moved I’m starting to think the sender unit

Sorry should of said full tank last night

My monti Carlo 1.2rsi is normally great on petrol doing between 46and 54 mpg and almost done 100k miles but today it used 1/4 of a tank todo 18 miles every once in while it dose on a short 20 mile journey do a low mpg any one have any ideas what could the problem be thanks in advance soamer