[losfer]

so my 99 (almost stock as a rock) jimny like others is a thirsty mule , about 10-11 litres per hundred . im hoping to reduce my fuel consumption slightly to get 5 trips to work and back rather than less than 4 1/2 trips.

All my driving is highway driving in a 110 km/h speed zone , i live less than 1 minute from the highway and work less than 1 min off the highway , so do 80kms a day in a 110 km/h zone with little to no traffic.

I am a window down with the fresh air blowing through my hair guy , but i plan to test the theory that window up with a/c on will reduce significant drag to better fuel consumption even though the a/c is sucking the horsepowers from my engine . i also plan to change to slightly narrower tyres to reduce road friction and wind resistance . i also plan to possibly juist cruise at 100 km/h rather than 110 , does anybody know the jimny's sweet spot of rpm/km/h vs fuel consumption ? have also considered a lot of other things which would slightly decrease fuel consumption but not significant enough for a mention.

according to a scan tool my oxygen sensor is sweet , my air filter is fine , i dont have a blocked catalytic convertor .

any suggestions welcome.

[J--A--C--K]

May or may not help but in a recent trip from Perth to Melbourne via Darwin and every where invetween .in a sierra ,The car was really loaded up , and with 30" muddies , at 80-90 kph we would get 10-11 leters per 100. And at 100-110 it would go as high as 16-17 . We loged ever fule stop , how much fule and distance ect , 16,000 Ks by the end . , I also read once that in most cars 90kp is the most effeciant speed , but that was off the net so not gospel .

[losfer]

yes that sort of info does help , thanks ..

[Skippy]

May be a bit of info, mythbusters once did a gig on a/c vs window down on a oval track in a patrol size ford SUV. Speed and distance traveled were matched and fuel consumption was better with a/c on.

This may not be relevant to a car our size, other things may come into play like wind, weight and and revs.

[Jezza86]

Skippy wrote:

May be a bit of info, mythbusters once did a gig on a/c vs window down on a oval track in a patrol size ford SUV. Speed and distance traveled were matched and fuel consumption was better with a/c on.

This may not be relevant to a car our size, other things may come into play like wind, weight and and revs.

its actually more realavent! the AC saps the produced power and the ac load (and corrisponding power sap is a function of the energy efficientcy of the body. our car bodies have a transmission tunnel that ducts heat into the floor, a lot of windows which let in the heat, and thin body pannels which also reheat the a/ced air.
our advantage is we have a lower air volume in the car to keep cool, but as you ditch things like carpet and heavy sound deadening you loose insulation and make the ac work harder.

with that said, most efficient, fan/blower off
2nd, small 12 volt computer fan blowing on you.
3rd, blowr on low
4th blower on higher sttings
5th blower on low, ac on
6th blower on high, ac on
7th window open
8th blower on, ac on, heater on, window open, subs making doof doof, hand out window.


a simplistic way to look at it (without using more accurate equations) is n(the drag coefficient of your jimny)*v(speed)^2.
the faster you go, the more drag there is, and your car is less efficient.

bottom line is:
higher pressures in your current tires, but nothing ridiculous, only a few psi over the manufacturers fully laden weight
empty the car of everything non essential. less mass to accelerate is less energy wasted.
the slower, the less friction, the better fuel economy unless your engine is laboring. it takes roughly 20Kw to maintain 100kph in an average car
siting on 80-90 (in a 110 zone) could be dangerous and you will have less fuell capacity if someone hits your car up the bum though
id suggest keeping a detailed diary and dropping your speed in 5kph increments. use 2 tanks of fuel per speed.
back off. every time you have to touch the breaks your pouring petrol down the drain. concidor backing off the power and reducing your velocity in a manner that reduces the need for breaks.
sometimes ll just drop it into neuteral and coast but thats not a good, safe thing to do.
gentle throttle increases, reving quickly uses more power
short shifting, changing the peak revs on a gear change saves some fuel so changing at 4500 max limits the fuel usage massively.
balance

[Mike57]

From my experience the wind resistance offered by the Jimny is the real killer. Best speed I have found is 90 kph. This gives me about 9.5 Litres / 100 km. Taking the speed up to 110 kph increase fuel consumption to 13 litres / 100 km. I just got back from driving 9,000 km and went through many tanks of fuel on the open road experimenting with this.

[31zook]

^this.

From my experience jimny motors don't mind pushing tyres around. With 80mm lift, 31s and a bar with lights I consistently get 10.5lph. Thats to work and back which is all 90kph or under. And I barely have the aircon on at all.

On highway trips I get about the same also... so go figure.

Before its asked, yes my speedo is corrected for tyres.