Hi Kane,
Just made the change from 2.0i sport to 3.0si sport. . .
I changed as the cost of tyres, road tax, insurance even servicing all manageable and 'fairly' similar over a years motoring (with a specialist rather than a dealership and being in my 50s insurance ok road tax £280) BUT I've found that the fuel consumption is the biggest difference:
I use the Zed mostly for trips out on our favourite roads at weekends - say 70 miles circular. On these trips with spirited driving I'm getting 21 - 22mpg. On the same roads using all the performance of the 2.0i I was managing 29mpg. I also use the Zed for trips shopping and general visiting friends locally and urban driving brings about 23 - 24 mpg. On a long motorway journey (200miles) at 78 mph I managed 36mpg (6th gear could do with being a bit longer and lowering the revs to be a true overdrive). The 2.0 would achieve high 30s and even 40+ on a steady throttle at motorway speeds and urban driving would hit 30mpg.
The 2.0 is more economical and with the mileage you're talking about I would estimate your fuel bill would be increased a third - which given an extra 2 cylinders does kind of make sense - however I had hoped for slightly better consumption from the 3.0 (the performance does make up for it though).
I haven't had my 3.0 long and am still enjoying the performance so driven more sedately I'm sure my mpg can be beaten - but then why buy a 3.0 to drive like that?
I have experimented and found that you have to try very hard to improve the urban fuel consumption more than 2 or 3 mpg.
I would be very interested to hear what others have to say? Does the 3.0i with 231bhp do more mpg than the 3.0si at 265bhp - if so that could be a better route for you?
I would stick to the 2.0 litre as a daily driver -
would you get the opportunity to use the performance of the 3.0 on a commute?