ZEL - Z Energy.

[Cyclical]

I only ever bought 91 at Gull, and there seemed to be a noticeable reduction in how far a tank lasted, compared to other brands.

Just checked their website: "Gull Regular 91 Octane petrol contains no ethanol and is less than 10 parts per million of sulphur."

It's unlikely that any additives are causing a decrease in economy. Interesting.... I'll ask some others about their experience.

Yep, it all means jack until you do an apples for apples comparison under controlled conditions.

Personally I'm happy running their 98 in my phase 2 tuned turbo, driven none too softly on a none too flat long trip between New Plymouth and Hamilton while easily returning 7 litres per 100km. The ethanol probably helps keep temps down and it's been tuned specifically for that fuel. No stuffing around with discounts and stacking. I doubt that running bp98 is going give me much more power and anywhere near the better economy required to compensate for the significantly higher price.

In my V8 M3 however, I insisted on bp98, but for the average Joe in their daily, who cares.

[Cyclical]

In 2013, Gull lost a tax case in respect of their use of blending butane into petrol to reduce the excise. Butane had an excise duty of 10 cents a litre and petrol was at 48 cents a litre.
They were blending in relatively small amounts in but attempting to save the 38 cents per litre in excise duty which saved them $10m in excise.
Customs disagreed and the Supreme Court upheld the Customs interpretation which meant Gull incurred $13m in penalties and interest for a total bill of $23m.

source: http://www.stuff.co.nz/business/indu...trol-tax-fight

At the time, expert evidence was that the blended spirit wasn't chemically identical to petrol. Butane has an energy density of about 7,700 Wh per litre and petrol is about 9,500 Wh per litre (for reference ethanol is 6,666.6 Wh per litre) so it would not have the same 'energy density.' E10 roughly has 9,200 W-h litre so it can have a higher research octane number (RON) but have less density so relatively the savings from using it are offset by the increased fuel burn.

Disclaimer - I don't know if the blending is still occurring or indeed what brew is live. I'd also say that actually getting reliable and accurate relative fuel economy comparison out of one tank of gas isn't actually achievable unless you have an identical car following you with the other gas, you do a particular long distance run with little traffic and similar driving styles to judge it (or you have the sort of data acquisition and logging you have on a race car) or alternatively do the test under controlled conditions like on a track - believe me I've spent a bucket load of time looking at it in the context of endurance racing - even a variable like tyre pressure, rolling resistance of different tyres, ambient temperature can all play a part (actually it's mainly the driver that makes most of the difference).

In terms of savings from the fuel discount programmes, by judicious and disciplined use of stacking in the Flybuys Z and Caltex Pumped scheme (e.g. buying in $40 increments and stacking), I have achieved an average discount per litre of around 22-23 cents per litre off pump price for all the petrol we have purchased since last August that's equated to about $550 off the pump price. That is across two cars but it represents about 4 times the discount most folk could access but don't because they don't know how it works or don't perceive that there is value in doing so - also $550 after tax is about $820 income pre-tax which for a lot of folk isn't small stuff - even half of that for most folk (say one car) isn't small stuff.

Good interesting read that, Rep, thanks.

[Jay]

Still don't really understand how this stacking saves you money - max you can save on is 50 litres, you are going to fill up more often to stack and hope when you need a full 50 litres there is a bigger than usual discount so may save a bit. Have to use the discount within 2 months max - the end of the following month??.

No talking about about having another family member paying full price and giving you the discount.

[Getty]

Its a bit like MMP and Single Transferrable Voting systems, a lot of people think they know what it means, until you get them to explain it..

[Zaphod]

Still don't really understand how this stacking saves you money - max you can save on is 50 litres, you are going to fill up more often to stack and hope when you need a full 50 litres there is a bigger than usual discount so may save a bit. Have to use the discount within 2 months max - the end of the following month??.

No talking about about having another family member paying full price and giving you the discount.

Stop #1: Purchase $40 of fuel, let's say that's 25 litres, stack the $0.06
Stop #2: Purchase $40 of fuel, let's say that's 25 litres, stack another $0.06
Stop #3: Purchase 50L for a full tank, using the current discount of (say) $0.06 plus your two stacked fuel savings, which saves you 50Lx(3x$0.06)

versus

Stop #1: Purchase 50L saving $0.06 per litre.

[gains]

Still don't really understand how this stacking saves you money - max you can save on is 50 litres, you are going to fill up more often to stack and hope when you need a full 50 litres there is a bigger than usual discount so may save a bit. Have to use the discount within 2 months max - the end of the following month??.

No talking about about having another family member paying full price and giving you the discount.

Time for some maths?

Say you're buying 91 octane at $2.00 for your 40L fuel tank.

If you fill your car every time and get the maximum $0.10 discount, you save $4.00 per full tank. Total cost to fill tank $76.00
Every time you go to the pump, you save $4 and that's the best you can do.

With stacking, you can accumulate $0.20 of discount each time you fill up, just no saving that instance. Total cost to fill tank $80.00 but discounts accumulated are double.
Now if you stack for 3 fills you've got $0.60 discount and on your 4th fill, you redeem the accumulated discount and the discount from that day. Making a total of $0.70 discount on that tank. Saving you a grand total of $28 for that fill OR $7 per fill.

0 fill stacking then fill: Saving $4.00 per fill or 40L
1 fill stacking then fill: Saving $6.00 per fill or 40L
2 fill stacking then fill: Saving $6.67 per fill or 40L
3 fill stacking then fill: Saving $7.00 per fill or 40L
4 fill stacking then fill: Saving $7.20 per fill or 40L
5 fill stacking then fill: Saving $7.33 per fill or 40L
6 fill stacking then fill: Saving $7.43 per fill or 40L

This example was done with a 40L tank as it made the maths easier and you didn't have that awkward 10L's of stacking you wanted to take the jerry can and fill up to get the 3rd stack.. but it proves that stacking saves money, which is my point.

The optimal stacking point would also be 4 stacks and 5th fill.. the saving returns after that get less significant but we get the point.

[Clints]

Stop #1: Purchase $40 of fuel, let's say that's 25 litres, stack the $0.06
Stop #2: Purchase $40 of fuel, let's say that's 25 litres, stack another $0.06
Stop #3: Purchase 50L for a full tank, using the current discount of (say) $0.06 plus your two stacked fuel savings, which saves you 50Lx(3x$0.06)

versus

Stop #1: Purchase 50L saving $0.06 per litre.

If it's $0.06 and I need fuel I will only put $40 in and stack the $0.06
If it's $.10 I will full the tank which usually allows me to stack three lots of $40 so I get $0.3 on that one day.

I have ended up with over $2 in the past.

[Zaphod]

If it's $0.06 and I need fuel I will only put $40 in and stack the $0.06
If it's $.10 I will full the tank which usually allows me to stack three lots of $40 so I get $0.3 on that one day.

I have ended up with over $2 in the past.

Yes, that's a better way. Was trying to keep the math simple and less time consuming.

This is why discounting is probably hurting Z.

[Rep]

Time for some maths?

Say you're buying 91 octane at $2.00 for your 40L fuel tank.

If you fill your car every time and get the maximum $0.10 discount, you save $4.00 per full tank. Total cost to fill tank $76.00
Every time you go to the pump, you save $4 and that's the best you can do.

With stacking, you can accumulate $0.20 of discount each time you fill up, just no saving that instance. Total cost to fill tank $80.00 but discounts accumulated are double.
Now if you stack for 3 fills you've got $0.60 discount and on your 4th fill, you redeem the accumulated discount and the discount from that day. Making a total of $0.70 discount on that tank. Saving you a grand total of $28 for that fill OR $7 per fill.

0 fill stacking then fill: Saving $4.00 per fill or 40L
1 fill stacking then fill: Saving $6.00 per fill or 40L
2 fill stacking then fill: Saving $6.67 per fill or 40L
3 fill stacking then fill: Saving $7.00 per fill or 40L
4 fill stacking then fill: Saving $7.20 per fill or 40L
5 fill stacking then fill: Saving $7.33 per fill or 40L
6 fill stacking then fill: Saving $7.43 per fill or 40L

This example was done with a 40L tank as it made the maths easier and you didn't have that awkward 10L's of stacking you wanted to take the jerry can and fill up to get the 3rd stack.. but it proves that stacking saves money, which is my point.

The optimal stacking point would also be 4 stacks and 5th fill.. the saving returns after that get less significant but we get the point.

Assume 91 is $2.00 a litre.
If you do the fill on a super pumped day and do $40 fill you give up $2 (10c on 20 litres) on the day to get up to $5 later. If you do 3 fills of $40 (which I can - incl 1 to 2 fills on wife's car) then you give up $6 on the day to get $15 later.
The discount expires at end of month following - so if you stack 19 fills over 2 months that's $1.90 plus 10c on day that's $2.00 so redeem for 50 litres.

Maths:
19 fills @ 20 litres for $40 = $760 at 380 litres
plus free fill for 50 litres (I have a 70 litre tank in SUV)
that equates to 430 litres
$760 divided 430 litres = $1.77 or 23c per litre.

Do that every 2 months it's $50 per month. Also helps I drive past a Z or Caltex every day.

[gains]

Assume 91 is $2.00 a litre.
If you do the fill on a super pumped day and do $40 fill you give up $2 (10c on 20 litres) on the day to get up to $5 later. If you do 3 fills of $40 (which I can - incl 1 to 2 fills on wife's car) then you give up $6 on the day to get $15 later.
The discount expires at end of month following - so if you stack 19 fills over 2 months that's $1.90 plus 10c on day that's $2.00 so redeem for 50 litres.

Maths:
19 fills @ 20 litres for $40 = $760 at 380 litres
plus free fill for 50 litres (I have a 70 litre tank in SUV)
that equates to 430 litres
$760 divided 430 litres = $1.77 or 23c per litre.

Do that every 2 months it's $50 per month. Also helps I drive past a Z or Caltex every day.

Stacking saves money

Hmm, I'm curious now.. anyone tried making the fuel provider pay you to fill your tank? (accumulated more savings than the price of fuel)