Have a look on autotrader at other 125i's and see what they are advertised at. You'll always get more money selling privately but it's not as convenient. I'd say as a general rule you'll get £2000 under the forecourt selling price if you part-ex and up to a £1000 more than that if sell privately, although the 125i is a rare car so not that many buyers out there. (so if the car would retail at £10k, you'd get about £8k part ex offers and £9k as a private sale).
The last time I sold a car I found webuyany price was exactly the same as the part ex price I got offered at every dealer I went to. BMW may not be interested in your car as it's getting a little old but it's worth a go. Birds and other independent BMW specialists will also buy your car off you happily without you buying anything off them, but they may not offer more than a part ex price. It's only a phone call to find out though so worth a try.
You may get a better price at BMW because they can keep your car and sell it themselves if they want. A VW dealer will probably have to send it to auction, so will offer you less. (I was trading in an immaculate low mileage Mazda MX-5 with VW main dealers and none of them could sell it as they could only sell used VW's, so they offered us poor part ex prices - sold privately in the end for £1200 more).
You will get more mpg from a diesel obviously but you'll only really save money if you are buying one at the same money (or less) than you'll get for your 125i. If you spend any more on the diesel car then you'll need to do a lot of miles just to break even.
I imagine that a 140bhp Scirocco would be cheaper to insure than the 125i and tax will be cheaper but don't diesels cost slightly more to service in general (never owned one so I could be wrong), but it will be a fair bit slower and not as nice to drive. (ie noise, front wheel drive, etc).
You could always ditch the run flat tyres, normal rubber is a lot cheaper and better, but it does leave you more vulnerable to punctures.
What mileage are you doing? A smaller engined petrol can sometimes work out cheaper than a diesel if your mileage is low. Especially as they are cheaper to buy in the first place.
As for servicing, check exactly what is needed as it could just be the inspection service (ie nothing) or brake fluid change. Although my 130i needed new plugs every 60k and that's not that cheap.
The last time I sold a car I found webuyany price was exactly the same as the part ex price I got offered at every dealer I went to. BMW may not be interested in your car as it's getting a little old but it's worth a go. Birds and other independent BMW specialists will also buy your car off you happily without you buying anything off them, but they may not offer more than a part ex price. It's only a phone call to find out though so worth a try.
You may get a better price at BMW because they can keep your car and sell it themselves if they want. A VW dealer will probably have to send it to auction, so will offer you less. (I was trading in an immaculate low mileage Mazda MX-5 with VW main dealers and none of them could sell it as they could only sell used VW's, so they offered us poor part ex prices - sold privately in the end for £1200 more).
You will get more mpg from a diesel obviously but you'll only really save money if you are buying one at the same money (or less) than you'll get for your 125i. If you spend any more on the diesel car then you'll need to do a lot of miles just to break even.
I imagine that a 140bhp Scirocco would be cheaper to insure than the 125i and tax will be cheaper but don't diesels cost slightly more to service in general (never owned one so I could be wrong), but it will be a fair bit slower and not as nice to drive. (ie noise, front wheel drive, etc).
You could always ditch the run flat tyres, normal rubber is a lot cheaper and better, but it does leave you more vulnerable to punctures.
What mileage are you doing? A smaller engined petrol can sometimes work out cheaper than a diesel if your mileage is low. Especially as they are cheaper to buy in the first place.
As for servicing, check exactly what is needed as it could just be the inspection service (ie nothing) or brake fluid change. Although my 130i needed new plugs every 60k and that's not that cheap.