Ron95 versus Ron97

Right, this entry is like... two months later than I initially planned to post. Two months is still within slacker time frame of "soon", so all is good. =P

I have been recording the time, mileage and amount of petrol I used to commute between home and office since my department moved to ulu place.

I have since satisfied my curiosity of the distance and commute time needed, as stated in the previous entry. Of course the distance hasn't changed since I have been using the same route and the commute time doesn't differ much as well since I am still driving as I always do.

This entry is about comparing Ron95 to Ron97, in terms of the fuel consumption and efficiency. I was curious about whether Ron97, having higher octane (more oomp!), would end up cheaper than Ron95 since more oomp equals to less fuel needed to cover the same distance?

Since 81.47%* of statistical data are made up on the spot (*including this one =P), or interpreted to suit one's agenda, it's therefore worthwhile to understand the data collection method, sample size, boundary conditions, factors included/excluded to derive the figure of interest.

Or you can just go collect your own data. =P

For the benefit of those who didn't read the previous entry and who are too lazy to click the link to read it (you lazy buggers! =P), here's a bit of background (I am a creature of habit so nothing has changed really):

- MyVi first generation 1.3L automatic transmission
- about 70% highway 30% city**
- mostly sticking to speed limit (usually about 5km/h over on highway =P)
- follow other vehicle at safe distance so no sharp braking and acceleration
- fill up at Shell when I have about 25% petrol left
- pump tires every 2nd or 3rd time I fill up petrol
- always fill petrol to full so amount of petrol filled equals to amount used for the distance covered, I record the numbers and zero the odometer

** interesting to note that time wise, it takes roughly 55% and 45% respectively to cover the 70% highway (including bridge) and 30% city

Sample size:
Ron97 = 11
Ron95 = 31

Okay okay, here are the figures you want to see:

Distance covered per litre of petrol:
Ron97 = 15.9 km/litre
Ron95 = 15.7 km/litre
(i.e. confirmed Ron97 more oomp, teeny-weeny bit)

Amount of petrol needed per kilometer (invert of the above):
Ron97 = 0.063 litre/km
Ron95 = 0.064 litre/km

Not much difference eh?

Let's commpare them in Ringgit. Data collected when Ron97 was RM2.05/litre (so 11 times is enough punishment for my wallet, I am not THAT curious =P) and Ron95 was RM1.80/litre, that's before the government stealthily rises the price. A meaningful distance to consider is 10,000 km, this is when a service is required.

After 10,000 km, amount of petrol used:
Ron97 = 629.9 litres
Ron95 = 637.8 litres

At RM2.05/litre and RM1.80/litre respectively, cost after 10,000 km:
Ron97 = RM1291.28
Ron95 = RM1147.99
(for new rate of Ron95 at RM1.85/litre, cost after 10,000 km = RM1179.88)

So, using Ron95 consumes more petrol but still costs less.

In case you are curious, based on my data, which really is just applicable to my driving style and commute route, it's only when Ron95 is RM2.03/litre that I am better off using Ron97, assuming Ron97 is still RM2.05/litre, that is.

If you want to find out that magic number based on your own driving style and commute route, what you need to find out is how much it costs you per distance for Ron97 and Ron95 respectively. Basically it's a y = mx graph where y = cost, m = gradient (RM/km), and x = distance. Smaller m means lower cost and m depends on the mileage you get (km/litre) and the petrol price (RM/litre), divide petrol price by mileage to get m.

Not sure how many people felt insulted by my explanation, no offence intended, just want to inform all level of people. =)

Anyway, sorry environment, poor me is wallet first green peace second, Ron95 it is for me. =P