I wouldn't, since you'll surely be hit twice on depreciation, TT& L, + many other costs, since the dealer will make more $ off of u.
Plus, you'll end up with a 2 years older car.
I would patiently wait & get a newer year model...

 

You really can't answer this question without having driven the R. What the V8 is worth to you over the V6 is something none of us can tell you.

I see a lot of people (who own the V8) say that no one ever regretted having more power—but that's not the question. The question is how much you're willing to pay for more power...

 

to me, the sound of the V8 is more than enough to justify the cost. the speed is a second factor.

the bank wont deny you a loan as long as you qualify. the dealer will most likely hose you on your trade in, so financially its probably not going to make sense. you're most likely going to have to pay a couple thousand out of pocket to cover the difference on your current loan.

 

I went through that conundrum last year - considered going to a SVR (or post '15R) mainly for sound and quad pipes, really, as I had the 5 litre XKR and I didnt really need that power. I was a bee's dick away from saying yes to one but it didnt have everything in it that my car has and it wasnt IRR, so I was paying $100K more to get a car I wouldnt like as much though it would have quilty seats, quad pipes, and more noise. I figured that I would enjoy the noise when accelerating from lights if I was at the front of the pack maybe 3 times a morning for about 3 to 4 seconds a pop, 5 times a week on my way to work. I would get to enjoy it a little on the weekend as well, but ultimately I was going to be getting about 1 minute's extra enjoyment a week for the $100K.

After rationalising it that way I just lost interest which is virtually a first for me as I normally cant stop until I have made the kill, but a lot of the reason for that is that my current car is exactly the spec and colour I would want in a replacement. I ended up blowing a bit on a VAP quad exhaust and had the pulley and tune done at the same time (again for noise, though the extra power is fun).