Fuelly? ?WTF? mpg readings are so low.

[electronumpty]

Hello All.

Over the last year I was using a mobile phone app to track my fuel costs.
I will input the data into Fuelly shortly as I am really confused at the other peoples readings on here and can't figure out if it's me inputting the data incorrectly or everyone on here has a lead foot?

I am now on the look for a replacement car (very short story - not) as my insurance company have just written off my car following an accident and their very bad repair of it.

So I started checking out websites to check owners fuel economy verses manufacturers stated mpg values, so I could get the most fuel efficient car I could get in replacement.

Firstly I compared what other people were getting with their VW Polo Dune (Cross) cars. They seem to be getting worse figures than me (55mpg over a years worth of driving) but were close enough to think I could get a more economical car and save even more money per fill up.

Hmmm. Maybe not so much, according to this site.

After a lot of research (6 car driving tests) I had narrowed it down to the Polo Bluemotion 2 1.4 with AC. Though on Fuelly this is not much better than my Polo Dune. (Cross). Only 5 mpg better!?
Even though the stated mpg of this car is meant to be 80+ mpg

I then checked the 6 other cars on my list (all purportedly less than 100co2 emmisions) in the UK that means no Road Tax. None of them (on here anyway) seem to fair better than my old car.

My Questions.
Am I doing something wrong?
Am I missing something obvious?
Is every car out there (even the electric ones) only capable of 40-60mpg?
Or does everyone on here have really lead feet?

Please help me understand.

Regards
Electro Numpty