the oil company's are stuffing us

Its a long story but ill keep it as brief as possible, back in march last year my old ford transit van decided it had enough, metal worm had eaten through large parts of the chassis reducing it to rust making it un-mot-able… so with a heavy heart i decided to scrap it and buy another van. Not wanting a repeat of the same corrosion problems i decided to go for a Vauxhall vivaro,
I was a little unsure of how the vivaro would measure up to the transit in the economy stakes, so i started making a note of the mileage every time i filled up, i would write the mileage on the back of the receipt, reset the trip meter and off we go, and i always filled up at my local “JET” service station
Anyway to cut a long story short, the vivaro was doing between 36 to 37 MPG regular as clockwork, then about 2 months ago i noticed the mileage dropped to around 32 MPG, i actually thought there may be a problem with the van, it diden’t seem to have the same umph as before…
Two weeks ago i decided to fill up at a different service station, i cant believe the difference, my van now performs like it did when i first got it, and based on 2 full tanks of diesel its back up to 37 to 38 MPG… Me being of a suspicious mind, i just wonder if some of the oil companies have bulked there fuel out with ethanol/bio fuel rubbish to offset against the falling price of oil…
Which is food for thought when it comes to filling our bikes up this season, i certainly wont be using my local service station for any of my vehicles…

anythings possible these days
everyone else seem to be a crook