If it wasn't for the daft issue I have with my foot (Morton's Neuroma) being irritated by the heavy clutch spring, I'd say for me upto 8 hours of driving.
I did Dorset to Northumberland without any issues other than my foot (and bladder) but you need to fill up tootled around the borders over the weekend then back to Dorset again no hotels or stopovers in the middle just the odd bite to eat and stretching of the legs.
The 3.0 is a very easy lazy engine to live with on long runs, the rest of the car would be much the same as your new +4
Oh yes and I was topless the whole way up and down, but did have the side screens on to reduce some of the wind.
