I’m new to this form, I’ve been saving hard for month and months and finally next month I’m able to afford a Scirocco

I’ve had my mind set on a 2.0 TDI or a 2.0 TDI GT, till yesterday as my mate has the Scirocco R 2.0 TDI bluemotion , as he was saying the others aren’t very economical
My only query is I drive 22.4 miles a week (which is 3.2 miles) a day to work and back)
Is it worth me getting a diesel or shall I get a petrol?
I was thinking the Bluemotion as I know the road tax is a lot cheaper and probably be cheaper to run
I just don't want to invest a lot of money into a car that isn't going to get its full use

Was wondering if anyone could give me some advice or shed some light
I currently drive a Corsa sxi cdti 1.3