Fuel use and exhaust problem

Hi guys, I have had my 850 glt for a few months now. I have an issue with fuel consumption, around town I am getting 20-22mpg, however I drive, on a long motorway trip I can get it up to 25mpg but no more! Is this normal or do I have a problem somewhere? Also, right now I think the middle section of the exhaust is blowing, would this affect the amount of liquid gold, sorry I mean petrol, the car is burning or not? Any advice on where to go to get an exhaust done? I can't stand kwikfit as they have stuffed up so many jobs for me in the past (perhaps the local branch is just useless)

A blowing exhaust would definately contribute to fuel usage

I mostly use Braydon Motor Co. to send me parts and get a local trusted mechanic to fit everything for me. You can google them they are in london.

any ideas how much difference a new exhaust might make? I'm 50/50 as to whether to keep the car or get rid for something less thirsty, obviously I don't want to do the exhaust before part ex' or selling it.

You should be able to get a lot more than 30mpg on a run so something is definately not right. A blowing exhaust as mentioned will affect the performance and economy (as well as possibly affect sensor readings that are then sent back to the ECU). Exhausts are not too bad, but being in the trade, I would definately say, avoid going for a replacement part by Bossal (poor quality)! Go for Walker or a German part by Eurocarparts/GSFCP and get a local mechanic to fit it, unless you can trust a local mechanic to get you a decent quality replacement. Having done this will help you with your fuel economy and will benefit you if you keep the car. My mothers exhaust blew a few years ago on her car and the fuel economy on the motorway was shocking to say the least. Out of desperation I got the job done at ATS who actually did a decent enoough job but at a price! Was worth it though in fuel savings on the return journey.