I used to put the premium diesels in my company cars (before the bosses insisted I buy the cheaper stuff), it did make a difference but not a huge one.
You'll maybe get an extra 10-15 miles out of every tank with premium diesel. My wife also used to use it her Audi A3 (about 4 years ago) and interestingly the premium fuel did NOTHING to alleviate the DPF problems that plagued the A3.
For what my opinion is worth, I'd stick with standard diesel, but from a quality provider i.e. BP, She'll, Esso.
Until fairly recent retirement I was travelling circa 38k miles per year over a 12 year time period. In that time I had a couple of V6 Discos, a 2.0 GTD Golf and a 3.0l S Jaguar XF. None showed any improvement in mpg or performance when using premium diesel. I had conversations with BP and Shell at one time asking them to provide me with data that would back-up the claims being made for premium fuel; they were either unwilling or unable to do this. In the last couple of years of Evoque ownership we regularly travel to Geneva in our SD4 engined car. I've tried both regular and premium fuel and again have found no discernible difference. My only preference and although unproved is to stick to the major brands of fuel as I'm led to believe that they contain superior additives to that of super-market own brand.
There is some guidance about fuel use in the online owners' manual. It indicates that diesel fuel should conform to European Standard EN590 - I assume, not having knowledge of such things - that both everyday quality brand diesel and performance diesel will comply. Although it also suggests that the highest quality fuel should be used, it also cautions about use of additives (presumably over and about those contained within pump fuels).
I believe that so called performance diesel has a lower ignition temperature which may be beneficial in some engines/climates but I doubt the SD4 is as temperamental enough for it to make any significant difference to mpg V extra cost.
My guess is that a judicious mix of quality brand diesel with a more occasional use of the performance version to give up bit of a 'clean up' is the way to go.
EVO Magazine tested premium fuel and hardly found any difference in performance or fuel efficiency. I only detect a real difference on my Kawasaki Ninja super bike; here the 12,000rpm limit and performance mapping does gain you some 5-10% in bhp
Tested for some time premium diesel on my freelander 2 (TD4 not SD4) and no change at all.
I agreed with the mail just over, premium fuel makes a difference on highly optimised engines where you have more horsepower at high rev and a more "raging" engine. I was driving a tuned Yamaha R1 on tracks for some time and depending on where i got the fuel there was a noticable difference, both engine feeling and lap time...
Never saw that on cars...
Don't know what the difference in diesel fuels is but I know that the 4 stroke 100hp Rotax engine we have in our tug aircraft gets upset if fed with premium (97 octane) unleaded instead of normal (95 octane). Knackers the engine apparently, so the (ex BAR/Honda F1) engineer who looks after it tells me. In what way, I am not sure though, I just take his word for it and feed it the cheaper stuff. So 'premium' fuel is not always a good thing for all engines it seems!