I use the cheapest Diesel, never tried premium but wouldn't think it will make a difference.
I put premium petrol in motorbike, as its pretty old, that makes it run better, and as its E5 its less likely to go stale when it's sitting over winter.

A quick update.

When I bought my RR, TDV8, 3.6, I did a 300km run home and averaged 9.6ltrs/100kms (29.5 MPG UK).

I ran some injector cleaner through the car using 1 ltr to around 40 ltrs Diesel. Did the same 300km run driving the same way and averaged 8.3ltrs / 100kms (34 MPG UK).

I did notice the car feeling a bit more responsive and smoother. Seems the injector cleaner had some positive effect.

I'll be using premium fuel if it's available, and using injector cleaner every few thousand kms.

Can I ask what brand of injector cleaner that you used. I think I will try some in mine Dec 2011 L322 Range Rover Vogue SE TDV8 Orkney Grey/Sand leather

I Used FACOM as that was what was available and least expensive. 30 Euros for a litre if I remember correctly.

I did read the ingredients of the various cleaners available in the shop and they were all very similar (not that I'm an expert in this)

I have found it is better to use a high concentration. 200ml in a full tank will have a negligable effect.

A full litre for under half a tank seemed to work for me.

Hope it works for you.

Many thanks Dec 2011 L322 Range Rover Vogue SE TDV8 Orkney Grey/Sand leather