That's pretty good, and no doubt at least twice as efficient as your old V8. Although 5.8 l / 100km isn't anything special as far as turbo diesel's are concerned, and I reckon it will be possible to get the GT Sport TDI down to around 5.0l / 100 km on a long run.
I have just refilled too after 830 km and discovered that my trip computer is a tad optimistic. It was indicating 5.7l / 100km, but when I did the calculation myself (it used 52 litres), it worked out at only 6.2 l /100km. Still, considering all the city driving I had done on the tank, it's not too bad. I'll do a long country run soon and let you know what I get.
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