Marlie, I know I've just responded to your PM with the below but will post here as some may find useful.
It does seems like your getting really stressed about this purchase which is a shame - first and foremost, choosing a new car should be a pleasure (which is why I do it so bloody often!)
I actually think you need to decide 100% on the car you want first as it's hard enough negotiating different deals and finance offers, never mid having to do this across different cars at the same time!
Not being 100% sure of the car could also make you 'appear' less serious to a car dealer because it'll be obvious that you haven't made your mind up. I've always said that my strategy when I'm ready to buy has always been is to be 100% serious and ready to do a deal there and then. It makes the dealer work hard for a deal and puts the real onus on them to close me down.... I often don't do a deal at that time because the offer isn't good (hence I didn't buy my E Class from the same dealer show sold me the SLS....their loss!). Also, I may have to do this two or three times on the same car in different locations to get an idea of where the real breaking point is! This can all take time and whilst I know it seems I just seem to get deals quickly and easily, the reality is that by the time I've posted on the forum, I've done a considerable amount of negotiating and/or research (and I still kick myself sometimes!)
Anyway, take your time, drive ALL the cars you've shortlisted and choose your favourite....and don't let a dealer push you into a deal like you've suggested above - theres plenty of cars out there, it's not a rare or short supply model and I assure you that you will be able to spec another one!
Once you've chosen the car, you can then work seriously on drilling down a deal on that car. You can then play different dealers and brokers off each other over the same model.
As for the Audi - well, the interest rate is OK (if not market leading) and yes, even a good rate will add up the interest if you're doing it over 4 years. It's a nice car too but I think there are better deals out there...the CLS deal is substantially better and I reckon BMW would beat that too.
But, if you like the car better than the others you've shortlisted, then you can only go for the strongest deal you can get on that model of car which leads me back to my first point and the need to decide that first then play a few dealers / brokers off against each other. At the very least, get yourself a Drive the Deal or Broadspeed quote and take that into your dealer to beat AND give you the low rate finance. That way you can be more confident that you're getting a good deal (and if they've already beaten that, you know you've done well).
Of the cars on your shortlist.....well, I've just bought two Merc's, I like the brand and therefore am probably biased towards that brand. However, M@rk will counter this and say go for the Audi....but he's just got an A7 so is in 'honeymoon period', and he had a really bad experience with Merc so some could say that is a biased opinion the other way (and not without substance either). In reality, they're all great cars, you could have a good or a bad experience and only you can decide...although do take note of Paul's (M3Fast) view of ownership as he's actually owned one for the last year.
Depreciation wise, I seriously think there will be little difference between any of the cars you've mentioned so I wouldn't let that sway your decision one iota.
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