Monday, 3 September 2012

More about petrol consumptions


As the last post talks about fuel consumption I will spoil a little the news of the summer and I will talk about the new Miata consumption.

As you can see those two are my yesterdays two visits to the gas station.
In total it shows a consumption of 44.17L at 64.51€.... it is not cheap at all, but it could have been worst since I did 590.5km

It shows a 7.48L / 100km (running at legal speeds and mostly using 120km/h highways) or 10,92€ / 100km, quite far away from my 7€/100km my LPG car makes.

If I make the maths using those figures:
GPL install = 1800€+IVA (VAT) = 2178€
Assuming it uses the same amount of LPG as my Octavia then we can see that we can save 4€ each 100km and 2178/4=544.5 meaning that I would have to make 54500km to break even.

Something that needs a lot of thinking though since looks like I would use almost half of the trunk for the LPG tank. :-( Unfortunately there is no other location to place it.

8 comments:

Albert Aymerich said...

So... you cannot change your car before 54000km or you will be losing money. :-P

Ander Otxoa said...

Well... it is going to be more like... I will not convert it (more drawbacks than advantajes in converting it to LPG)

Albert Aymerich said...

Je,je... the main reason to convert or not convert can not be "an investment on your car"... it should be an investement on your life.
I mean, if the LPG conversion costs 2000€, you should ask yourself: How much time I need to save and recover 2000€?.
The answer will give you the "ROI"... and I think that you don't need 54000km or 4-7 years using car to recover that money. :-D

Ander Otxoa said...

MMmmmmm interesting point of view. However I may be missing something from your point so let me explain mine applied to this very car (the Miata), however for other vehicles it may vary considerably:

As from tradicional literature ROI = (Benefits - Cost) / Cost

So lets try to measure the Costs first since it may be the easiest one.
Costs:
Installation = 1800€+IVA (21%) = 2178€
LPG Maintenance = Aprox 1 maintenance session each year at 100€ each one (we will leave the number of years as a variable to make different projections later)

Now the difficult one, the Benefits (potential ones as they have not been produced so one again, difficult to measure):

Benefit in running price each 100km = 4€ (as seen in previous calculations) and we will use here an average of 15000km for each year (at the end of the day it is just a recreational vehicle) = 15000 / 100 * 4 = 600€

Enviromental advantajes = 33% reduction in CO2 emissions for each liter of fuel (*1) = To measure it we will take the aprox figure of 15€ per ton of CO2 (*2) so each year LPG = 15000km / 100km * 9litre = 1350 L * 1.5 Kg/L = 2025Kg CO2
Petrol = 15000km / 100km * 8litre = 1200 L * 2.3 Kg/L = 2760Kg CO2
This makes 735kg less per year = 15€ * 0.735 kg = 11€ per year of benefits

Maintenance advantages = more live to your engine since detonation in the chamber is softer (25% more aprox) = In a prospect live of 15 years this would be = 8000€/15y = 533€/y * 15y * 0.25 = 2000€ / 18.75 = 107€ per year

Fun factor = This looks quite difficult to measure but we will try anyway, this is the fun we have becouse of isntalling LPG becouse:
It makes the engine run smoother = 0.5h / week
It makes you be in the state of the art of alternative car fuels = 0.5h / week
It lets you be proud of yourself (mean! I know!) as you show it ot your colleages = 0.5h / week
This makes 3 hours per week = 1.5 * 52weeks / year = 78h/year and an average cost (*3) of 5€ per hour = 390€ / year


Initial figures
B = (600€ * Y) + (11€ * Y) + (107€ * Y) + (390€ * Y)
C = 2178€ + (100€ * Y)

Projection for 2 years
B = (600*2)+(11*2)+(107*2)+(390*2) = 2216
C = 2178 + 100*2 = 2378
ROI = ( B - C ) / C = (2216-2378)/2378 = -0.068

Projection for 5 years
B = (600*5)+(11*5)+(107*5)+(390*5) =5540
C = 2178 + 100*5 = 2678
ROI = ( B - C ) / C = (5540-2678)/2678 = 1.069

Projection for 10 years
B = (600*10)+(11*10)+(107*10)+(390*10) = 11080
C = 2178 + 100*10 = 3178
ROI = ( B - C ) / C = (11080-3178)/3178 = 2.49

RATIONALE
As seen by the previus figures it paysoff in just a tad more than 2 years and makes real advantages at 5 years.
However a lot of assumptions have been taken anf of course "your mileage may vary" ;-)

(*1) http://www.mynrmacommunity.com/motoring/2007/11/19/lpg-vs-petrol/
(*2) http://www.co2prices.eu/
(*3) http://www.payscale.com/research/ES/Country=Spain/Salary

Albert Aymerich said...

Wow!! what a detailed information! :-)

Yes, I agree on all with your calculations. This is the ROI considering only LPG and related data.

But, I'll try to show you another point of view (a broader one, I think)... Please, consider that I'm simplifying (just take the concept).

To me, the "advantages" could begin when you can recover the money invested in some thing, in this case, the LPG conversion.

For example, if you save 500€ each month, you will need four months to the 2000€. That is, in 4 months, you will recover the money spent on the conversion, and then your standard of living is again the same as the beginning, but this time you have a car with LPG. After that, if we compare with a car without LPG, obviously you are saving money.

If we agree that the standard of living can be directly proportional (simplification) to your savings, then lets do some (very)basic numbers:

SL=standard of live
SLm0=standard of live at month 0
In month 1, you make the conversion that it costs 2000€; so at that time, the standard of live could be:
SLm1=SLm0-2000€ (you are 2000€ poorer)
If you can save 500€ each month (I'm considering that you have an estable job):
SLm2=SLm0-1500€
SLm3=SLm0-1000€
SLm4=SLm0-500€
SLm5=SLm0 !!!! At the 5th month your SL is the same as you had 5 months before!! but also with a LPG car and its benefits.


As an example, recently I have changed my car. The new one uses less gasoline, but I don't think that I will have real advantages in, may be, 20 years (considering only the saving on fuel consumption).
I will have real advantages when I can recover the cost of the car (2-3 years)...well, honestly, since the first day I will notice the advantages. ;-)


(c)Google translate

PS: vaya tocho me ha quedado :-D

Ander Otxoa said...

He he he he after all that trouble, the reality is simpler than anything.
The reason I am not going to do it is this: (check the photo in the link)
http://i148.photobucket.com/albums/s4/stilletto_Rebel/FuelTank2.jpg

I do not want to occupy all the trunk with the LPG tank and there is no other place :-( ;-)

Ander Otxoa said...

This is the website of the guy who did what I won't :-)
(Not exactly the same car but similar)
http://mx5cartalk.com/forum/viewtopic.php?f=57&t=54163

Albert Aymerich said...

Yes... it's a bit BIGGG!! :-D

Flying in the AVE