MikeAqua:

 

I would just use 79c/km.  It's the IRD rate.  Close enough.

 

That's now 95c/km  

Tatou:

 

Started the half fill when petrol price were volatile ( bit like spreading your currency buy :-) )

 

Price was $2.537 for 23.84l total of $60.1

 

Cost to get there and back 14km  Car is a Hybrid getting 4.9l/100 hence .049l per kilometer which is .68l for 14 kilometers which is $1.74 hence Total cost is $61.74 

 

Cost of nearest station in Karori today BP is $2.92 a total of $69.61. 1 kilometer to BP hence .049l which is 14c. Total cost is $69.81

 

 

 

Saved $8.09 going to Caltex against nearest station  

 

but if you put in the car operating cost of $0.95/km (even $0.79/km) for 14km, you've lost. isn't that right? and that's before you factor your time in.

nitro:

 

but if you put in the car operating cost of $0.95/km (even $0.79/km) for 14km, you've lost. isn't that right? and that's before you factor your time in.

 

Depends whether the 79c is the total cost of a km, or the marginal cost of an extra km.  Also depends on whether this is the maximum allowable by IRD or an actual figure.

It seems unlikely that a hybrid car using $1.74 of petrol for this trip would incur an actual marginal cost of $11.06.  Maybe 2-3x petrol cost is more realistic

Net saving is probably still less than minimum wage for the time spent saving it though

shk292:

 

Depends whether the 79c is the total cost of a km, or the marginal cost of an extra km.  Also depends on whether this is the maximum allowable by IRD or an actual figure.

 

It seems unlikely that a hybrid car using $1.74 of petrol for this trip would incur an actual marginal cost of $11.06.  Maybe 2-3x petrol cost is more realistic

 

Net saving is probably still less than minimum wage for the time spent saving it though

 

sure. but the point is not to look at just the cost savings at the pump.

nitro:

 

Tatou:

 

Started the half fill when petrol price were volatile ( bit like spreading your currency buy :-) )

 

Price was $2.537 for 23.84l total of $60.1

 

Cost to get there and back 14km  Car is a Hybrid getting 4.9l/100 hence .049l per kilometer which is .68l for 14 kilometers which is $1.74 hence Total cost is $61.74 

 

Cost of nearest station in Karori today BP is $2.92 a total of $69.61. 1 kilometer to BP hence .049l which is 14c. Total cost is $69.81

 

 

 

Saved $8.09 going to Caltex against nearest station  

 

 

but if you put in the car operating cost of $0.95/km (even $0.79/km) for 14km, you've lost. isn't that right? and that's before you factor your time in.

 

Anyway it is worse as I just walked past the BP and it is $2.82 hence total cost would be $67.22 hence difference is $5.63 difference

Adding in operating cost of 14x.79 - $11.60 - BP operation cost of $.79 so a operating cost of going to Caltex of $10.81 

Hence Total Caltex is $71.70 and BP is $68.01 assuming a special trip for 14k If I filled the tank then even including operation costs Caltex would be $1.30 cheaper.

Anyway this is why I was looking for a formula that would account for such variables. 

What does the operating cost include as the car would otherwise be sitting in the garage?

Lesson so far- fill up empty tank or program a trip on Wednesday that would go past Caltex anyway

MikeAqua:

 

I would just use 79c/km.  It's the IRD rate.  Close enough.

 

IRD rate for 2023 is actually 0.95c/km

My Corolla costs 26c per KM. That excludes the cost of the actual vehicle. That's my annual costs divided by the kms. 

I also live in Auckland but probably every third tank is out of Auckland. I just fill up at Gulls (and their variations), I don't actually think I would save any money by going elsewhere.

Past 4.5 years I've bought 9524L of 91 at an average of $2.247

Obviously this is for work use, and there are a couple of caveats, I usually fill up when empty, but other times I like to have a pretty full tank, IE before the Waioeka Gorge on the way to Gisborne. But I also prefer to start my work trips with a full tank, as I generally know exactly where I'll fill up again. 

DjShadow:

 

I would enter what you've put above into ChatGPT and it'll give you an answer

 

ChatGPT isn't the best at math. As an example, I asked it this:

eracode:

 

Tatou:

 

My practice is fill up the car when the tank is half empty. I do make a special trip to do so unless I happen to be driving pass the refill site that is offering that best price in the area. 

 

Interested to know why you fill up when the tank is half-full.

 

Acknowledging it stuffs up maximising fuel discounts but from an emergency perspective you should always have half a tank and try to do it myself.

As someone who was without power and fuel that couldn't get delivered into the region post Gabrielle for days you never know when you don't have the luxury of filling up.  The queues around the only petrol stations who were able to source a generator to power the pumps and were forced to ration supply looked horrific.  Side note, you should always have a spare gas bottle for the BBQ ready to swap over as gas bottles were in very short supply even after a main road reopened and power restored.

The theoretical 2am phone call that a relative is hanging onto life a region or two away.  Emotionally driven you immediately jump in the car and just drive, you realise you have no fuel and find a lot less petrol stations are open overnight than you remember.

Not letting the tank get too low so the crap lurking in the bottom of the tank doesn't get stirred up and clog things up.

JPNZ:

 

IRD rate for 2023 is actually 0.95c/km

 

95c/km it is then.  Shows how carefully I (do not) check the payments for my mileage claims!

Here is a simple example.  Let's say I need 40L of fuel (half a tank).  Every km I drive costs me 95c.

For every extra km I drive to reach cheaper fuel, the fuel needs to be 2.4c/L cheaper.

If I drive 5km out of my way the fuel needs to be about 12c/L cheaper.

Obraik:

 

DjShadow:

 

I would enter what you've put above into ChatGPT and it'll give you an answer

 

 

ChatGPT isn't the best at math. As an example, I asked it this:

 

...snip...

 

MikeAqua:

JPNZ:

IRD rate for 2023 is actually 0.95c/km

95c/km it is then.  Shows how carefully I (do not) check the payments for my mileage claims!

Here is a simple example.  Let's say I need 40L of fuel (half a tank).  Every km I drive costs me 95c.

For every extra km I drive to reach cheaper fuel, the fuel needs to be 2.4c/L cheaper.

If I drive 5km out of my way the fuel needs to be about 12c/L cheaper.

 

 

Groucho:

 

Not letting the tank get too low so the crap lurking in the bottom of the tank doesn't get stirred up and clog things up.

 

Hmmmmm...............   let's think about that.

The fuel is always taken from the bottom of the tank, right where the "crap" is that you're worried about.

Unless the fuel pickup is on a float (I don't know of any that are) it has to be like this otherwise you'd never empty the tank and  be able to get the quoted range out of the vehicle.

IMO it's an OWT about not running your tank low to stop getting  your fuel system clogged up with crap.

I don't make a practice of keeping the fuel low in my tank but I very often get to within a litre or two of empty before I refuel.I fill about once a week. Never had a problem with crap in the fuel.

However, having a nearly empty tank repeatedly for long periods especiallly with a metal tank increases the chance of condensation forming inside the tank and so water will build up in the fuel tank. This will eventually cause a problem and when it does it won't matter how full the tank is.

Not sure where you are but I am in Porirua and Gull stations in Lower Hutt are a full 30-40c cheaper per litre than Porirua

On a full tank of a 60L car that is a $12 saving assuming my tank is empty, if I am in the Hutt for some other purpose, I will fill up there, but my time is worth more than $12