FYI, I would have a V6 over my JTD in an ideal world, also I've not said I could out pace a V6 in a straight line, I appreciate your comments regarding 0-100 as a performance metric, I've had no trouble extracting the performance out of my cars too, I managed the following figures out of my cars at Santa Pod.
GTA 1/4 mile 14.1 99mph terminal
GT 1/4 mile 15.6 90mph terminal
I doubt it takes another 5 secs for me to hit 100mph, I would fancy my chances against a 159 Q4 3.2, when I test drove a Brera Q4 it felt like the Brera took longer to hit 100 versus my GT JTD, said as much Here (Just borrowed a Brera)
For me most of my roads are A and B stuff, there are no notable straights its all about how well the car handles and there can be no denying that both cars GTA or GT JTD are far from optimal and that for the day to day driving that most do even when driven pretty spritely both cars would be achieving similar speeds, its all about what you can carry through the corners and peformance out of the them, with short gearing and lots of torque the JTD is pretty rapid out of a bend and can hold its own through it, a GTA won't be accelerating away as if I'm standing still.
Assuming my car is fit and healthy and I still own it I don't mind demonstrating the JTD to anyone who fancies a passenger ride, I'll be a Castle Coombe 30th April
I won't mind if a stock GTA comes along to see how much quicker it is a lap, I don't think it will be as much as people think, the only section it falls down on is the straight topping out at 120 whereas I'd do >135 in a good petrol though a GTA is probably not as quick at the top end as some of my other cars.
Rambling on as I do
, my basic point is that for what it would probably cost to change he could sort his JTD and have a very capable car that doesn't cost the earth to run and is enjoyable, if he buys a GTA it would still need sorting for decent handling, for some here diesel is the devil for me I less fussed about the fuel and more so about how good the engine is whatever fuel its on.