I'd suggest going and test driving those 4, see what you think.

Regarding the BMW : be a little bit cautious. The 'official' service intervals for oil changes (roughly 18-20k) are not really enough, and can lead to engine/turbo/timing chain failures past 60-100k miles. If you do get one of those, make sure you get oil changes done every 10k or so. Also, I'm surprised the insurance quote for that is so steep. I've got a 2013 (new shape) 325d msport touring, and am only paying £230 a year (low - rural - crime area, and have 10+ yrs NCD).

Perfect question put there Harish, all the info anyone needs.

My only suggestion consider Kia Optima too, 7 year 100k mile warranty.

Out of your 4 choices i wouldn't choose number 1, reason being its previous extended service intervals leading to future long term reliability, others will disagree with that.

For £15K you could buy a one year old KIA Optima (rebodied and slightly lower-spec Hyundai I40) from a dealer - which will still have six years of its original manufacturer's warranty left. Hunt down the mid-range "2 Tech" model which is very well equipped. Cheap to run (50+ mpg), quick enough (0-60 in 10 secs, 125 mph) and all the toys you'll ever need. (voice controlled bluetooth interface, touchscreen sat nav, reversing camera, heated seats.) there only one engine option the 1.7 CRDi.

Yes the BMW and Mondeo are better cars - but the KIA is by no means bad. The press slate the C3 compared to its rivals - but as you've found out, it's a perfectly good car. It's hard to find a genuinly poor car these days and the differences between 1 and 5 star rated cars are usually down to nit-picking. Drive one and see what you think. The Honda Accord feels a generation older than the best in the class as does the KIA - which doesn't make them bad despite what the press think! The i40 is too a slightly better car than the Optima but it will only have originally come with a 5 year warranty and will be older for the money.

Also don't overlook the Vauxhall Insignia - they are excellent cars - really good looking too but with wicked (typical Vauxhall) depreciation making your £15K go a long way - you'll easily find a one year old Insignia 2.0 CDTi with 10,000 miles on the clock for about £12.5K - I don't know why they depreciate so quickly because they are right up there dynamically with the best of the rest.

If you go for a Ford, consider a Focus if you don't need the extra room in a Mondeo, which is a big car. The 2.0 TDCI is a better performer than the 1.6 and almost as economical.

With that distance to commute, you need comfort, so consider a Volvo S40 or S60. I agree with the others - don't go for the BMW, not only because of the servicing issue, but they also hold their value and so your budget would run to an older car than the other makes you're considering.

The same goes for Audis and Mercedes, although you can get a similarly-powered Skoda or SEAT for less money than an Audi. I'm a little biased as I've had three of them in succession, but you could put the Octavia on your shortlist. After 2009 the common-rail diesel engine was fitted to Octavias, and the 2.0 is a good engine.

If you are satisfied with your current car why not keep it and buy your wife another vehicle? Your wife will be starting without a no claims bonus so she will need to build that up so a low insurance rating is a consideration.