Not wanting to worry you and no particular reason to ask but are you positive the mileage is correct?
My calculations are based on brim to brim refuels with the mpg being calculated on miles driven and fuel put in, not the trip computer. I also record the trip computer readings as well as the calculated mpg and the Brera is pretty similar but the GT readings could be a 2 or 3 mpg out.
This is then averaged out over the life of the vehicle when I've owned it. I have a maths/stats degree from a "proper" university I so am pretty sure about my calculations.
I'm not thrashing it, but I'm comparing it to my GT and the style of driving is the same. It should be better than the GT, not taking the 19" shoes into account.
Thanks for the offer. I've got an Obd2 wifi reader, but only used it with my iPhone with limited joy. I'm on holiday at moment, but may bring my work laptop home when I get back and put some proper software on.
It's been scanned at a main dealer, so I would have thought they may have picked up on any DPF/Egr issues. They've offered to open a case with ARUK as it needs to go back in to look at a little leak in the boot again, but it's not the "usual" Brera leaky boot as reported on here frequently.
The garage is reluctant to look at anything under warranty unless the computer says its broken.