Fuel economy - some figures

Submitted: Monday, Feb 28, 2005 at 13:17

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Cruezr

G'day all.
Another post on the fuel economy (or lack thereof) of an 80 series 4.5L petrol (ex-gas) manual. Vehicle was originally fitted with 105L gas tank and standard 95L (80 useable) petrol tank. But after a lot of reading and around $2K of engine repairs with only 165K on the clock, I ditched the gas tank and installed a 166L long range petrol tank. From December 2004, I started using PULP (98 octane) to further improve fuel economy and power.
These figures have been gathered from average driving over a 3 year period and consists of about 80% highway driving and 20% city driving.
GAS: 4.8 km/L = 20.8L/100km = approx. 10c/L @ 47.9c/L
ULP: 5.6 km/L = 17.8L/100km = approx. 17.8c/L @ 99.9c/L
PULP: 6.2 km/L = 16.1L/100km = approx. 17.5c/L @ 108.4c/L
Fuel prices are based on last weekend's prices in Bairnsdale (East Gippsland).
As can be seen, there is obviously a big jump in running costs between gas and ULP, but PULP is a little under 2% cheaper than ULP, with the increased benefits of more power and a cleaner engine but its availability is more restricted - but not a problem in city areas.
Obviously, there are a number of other factors that need to be considered in the global picture of fuel economy (and I haven't gone anywhere near the oilers).

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Reply By: Cruezr - Monday, Feb 28, 2005 at 13:22

Monday, Feb 28, 2005 at 13:22

A follow-up to my original post.
The running costs of 10c/L, 17.8c/L. 17.5c/L should actually be c/km.

AnswerID: 100484

Reply By: Savvas - Monday, Feb 28, 2005 at 14:42

Monday, Feb 28, 2005 at 14:42

Hi Cruezr ...

I get a similar result using 98 octane (eq Optimax) over ULP in a 3.5V6 Jackaroo. As an average since beginning of November last year, I get an 8.6% consumption reduction.

It works out close to line-ball $wise though for me.

AnswerID: 100495

Follow Up By: Cruezr - Monday, Feb 28, 2005 at 16:49

Monday, Feb 28, 2005 at 16:49

Hi Savvas
Using my figures, my consumption reduction is about 9.5% for the same kms travelled with a corresponding fuel price increased of about 8.5% - putting me about 1% better off overall. Not much in dollar terms but at least the engine is running better, more power, less deposits.

FollowupID: 358674

Follow Up By: Member - Davoe (WA) - Monday, Feb 28, 2005 at 17:26

Monday, Feb 28, 2005 at 17:26

pulp allows the engine to run a more advanced timing rather than be retarded by the knocksensors on lower octane fuel hence the better economy and power. It does not come only from having more BANG in your fuel

FollowupID: 358681