I did some numbers and posted this in the other van thread as well:
Petrol v's Diesel:
If the new van costs $3500 more for a diesel, that buys around 2690 litres of petrol at around $1.30/l
That is equal to 22.435km in the petrol version. this means that you will get at least 22.000 km of free km using your petrol van in comparison!
In the time you do 22,000 km in your petrol van you would still have to pay for fuel in your diesel. @ 8L / 100km you will use around 1760L of diesel. @ around $1.40/L this will cost around $2460. So now you are nearly $6000 worse off with the Diesel!

I guess it may take a lot of drivers between 1-2 years to do 22.000 km.
So if you do around 22,000Km a year you can save around $1000 a year in fuel cost. Therefore it will take at least
another 6 years before you even
break even on the difference in purchase cost, on the fuel saving.
After that initial
seven years and 154,000kms (it make take longer than 7 years if you do less KM/year), yes, you now actually save $1000 in fuel costs per year/22000km.
That's
if you even still have that vehicle after it has done that 154.000km!
Bear in mind that Diesels typically cost a huge amount more to recondition or repair the engine when it gets to the end of it's life (worn out or broken). Balance that against the general longer life for many diesel engines, but it really all boils down to the fact that for most private, non commercial use owners, you may never get back the initial higher cost of buying a Diesel new.
And the pertol V6 version will go a lot quicker, quieter and smoother.
PS. I just realised that Toyota claim 8.2 and 8.4L/100 for their Diesels, so my figures are actually slightly optimistic.
New Toyota Petrol v's Diesel? No contest!