Bad maths there, Ron. The fuel consumption figure should be based on the difference in fuel economy.
Let's assume the Td5 gives an average of 11litres/100km and the V8 22litres.100km - that's a difference of 11 litres/100km. So you can double the distance you've given, i.e., 38,000 litre @11 litres/100km = 354,454km. (And we haven't taken into account the cost of diesel which is much higher.)
We won't mention the higher servicing costs of the diesel. OH, damn, I did. :(

