I am considering trading my petrol vehicle for a diesel as I have
started a new job which means I will be clocking up approx 300-800kms
per week.  Please note this question relates to prices in New Zealand
only

Taking into consideration the additional costs of running a diesel
vehicle over a petrol:
1) Road user charges (apt to change at the whims of government)are not
applicable to petrol vehicles.

2) Services are more frequent and more expensive than petrol vehicles.

Could you please assess these expenses and relate them to a "cost per
litre" basis, e.g. taking into consideration the extra frequency and
costs of servicing a diesel and road user charges - this would add
$??? per litre of diesel.  This would give me an accurate indication
of the "true" per litre cost of diesel in comparison to that of petrol
- then I will know whether to trade my current vehicle in for a diesel
or to keep it!!

Many thanks

1stflight

<According to AA PetrolWatch, the cost of running a new petrol car
with fuel consumption of 10 kilometres a litre is $1.00 more per 1,000
kilometres than an equivalent diesel vehicle.

This saving won?t necessarily offset the increased servicing costs an
older diesel will incur.

The days of cheaper diesel running costs compared to petrol are
probably over for some motorists driving older diesel vehicles.
Source: The New Zealand Automobile Association
https://www.aa.co.nz/media/media/Section?Action=View&Section_id=252&Story_id=3106

According to AA PetrolWatch, petrol has risen 32 cents per litre, and
diesel has risen 35 cents per litre, since the beginning of January.
https://www.aa.co.nz/media/Section?Action=View&Section_id=252&Story_id=3270

The New Zealand government has an online calculator that will allow
you to work out how much a particular car, engine size and fuel will
cost.
http://www.fuelsaver.govt.nz/>

The AA offers a running costs comparison. It is free for members and
cost $7 for non members.
http://www.aa.co.nz/motoring/Section?Action=View&Section_id=275

According to the AA,  a petrol car needs servicing every 10,000 km and
a diesel every 5,000km.
The price of a bronze service is $110.00.
http://www.aa.co.nz/motoring/Section?Action=View&Section_id=154

Road user charges.
$32.15/1000km
Source: NZ government.
http://www.ltsa.govt.nz/publications/docs/road-user-charges.pdf 

You will be travelling approximately 40,000 km.
Petrol servicing. $110 x 4 = 440   per litre = $0.11
Diesel servicing. $110 x 8 = 880  per litre = $0.22
Diesel RUC = 40 x 32.15 = $1286

Diesel
Additional costs for servicing/year are $440
Petrol savings are $40/year
RUC $1286
Additional costs for diesel per year = $1686>


<Search strategy:>

<nz petrol diesel cheaper>
<://www.google.com/search?hl=nl&rls=GGLG%2CGGLG%3A2006-12%2CGGLG%3Aen&q=nz+petrol+diesel+cheaper&lr=>

<Hope this helps.>

Well researched and good consideration given to query

I assume you know that diesel fuel is cheaper than petrol, since you
talk about maintenance costs. If you're thinking about it for the long
run, I assume diesel would be cheaper, since petrol vehicles are not
designed usually for long hauls and hard power. Diesels are expensive
in maintenance, but more designed to be robust and long-lasting, so
when the whole time is over, I believe you spend less with diesel. If
you're thinking of the short-term (using a car for a year then getting
rid of it immediately after), petrol would be cheaper.