The AX Eco Project : 100 mpg target !

[2007 ion2]

the taller tires and gearing makes your speedometer and odometer readings invalid, unless you re calibrate it, so how are you calculating your consumption?

[HypermilerAX]

My speedometer is more correct with the taller tires.

With stock tires :
Speedo : +9%
Odo : Correct

With taller tires :
Speedo : +3%
Odo : -6%

Measured circumference under load :
155/70 : 1715 mm
155/80 : 1820 mm

I simply apply a 1.06 factor (also verified on daily trips before/after tire change) on the distance to calculate the consumption. As simple as that.

[renault_megane_dci]

Did you quit using the car ?
What's your consumption these days ?

[HypermilerAX]

No, I use it more than ever. 21000 km in the 2nd semester of 2013. I just don't update my fuel log here, look at spritmonitor. I get just aroud 3 l/100 km at 90 km/h but the winter hasn't been very cold so far so that helps. I haven't done anything new on the car.

Also, about the oil, for the last change I tried 5W40 instead of 15W40. I was really surprised how that affected the behaviour of the engine when cold. It starts much easier now (it was already starting good), like when the engine is already warm. The lower viscosity of oil when cold does the trick. The engine is spinning much more smoothly during the first kilometers, I also have more power. The 15W oil under 5°C must be like paste, the 5W is much less viscous.

I don't expect any consumption improvement with this, if any it will be in the variations. If the oil consumption remains acceptable, the fact that it lubricates the engine better on startups is a reason enough to use it.

[Jyden]

Impresseive milage. You really got a 3 liter car (3 l to 100 km), which is amazin considering it age. Just proof of what a lot of modding and a persisten mind can do...

[renault_megane_dci]

Originally Posted by HypermilerAX

No, I use it more than ever. 21000 km in the 2nd semester of 2013. I just don't update my fuel log here, look at spritmonitor.

Originally Posted by HypermilerAX

Also, about the oil, for the last change I tried 5W40 instead of 15W40. I was really surprised how that affected the behaviour of the engine when cold. It starts much easier now (it was already starting good), like when the engine is already warm. The lower viscosity of oil when cold does the trick. The engine is spinning much more smoothly during the first kilometers, I also have more power. The 15W oil under 5°C must be like paste, the 5W is much less viscous.

I don't expect any consumption improvement with this, if any it will be in the variations. If the oil consumption remains acceptable, the fact that it lubricates the engine better on startups is a reason enough to use it.

Yeah, less viscous oil allowed my old 1.9D Clio to realize a part of its economy potential (not impressive @ around 5 liters / 100 kms)
One need to be careful on this topic

I don't recall if you did insulate the sump or add an engine tray ?
Sounds like good winter mods.

[NothingFace]

I have a Citroen AX 1.5d like yours and hope I can get MPG figures like your's and maybe start modding.

Do you find its better to pulse and glide or to keep constant speed on the ax ? (on a flat road that is)

[renault_megane_dci]

It very much depends on your use of the car.
Long and steady slow speed commute to work do wonders when short in town operation is a killer.

[jsp1990]

hi, sorry for the bump. which gearbox are you using? how tall did you make the 5th gear to achieve such low mpg?

[HypermilerAX]

Hi, the code is 20CB98 but with a custom 5th gear out of the 1.4 HDi engine which is 12.7% higher. I also have bigger tires. By the way, I will make an update regarding this because things changed on the car. I had 155/80 R13 (+5.7%) fitted but wanted to mount the nice Ecopia's 145/80 R14 (+7.4%) from the Audi A2. I have now exactly 45 km/h per 1000 rpm versus 37 originally, that is 21% more.
My goals have changed with the car. I don't aim anymore at super high mileages like 100 mpg or anything near that. Actually, I drive a lot faster (read : at PSL on country roads and 100 to 130 on freeway depending on mood and how in a hurry I am) and removed mods to make the car as civilized as possible.
To fit the 145/80 R14 was actually more motivated by the look of the tall and narrow tires than by the potential mileage gain. To fit them, I had to find 14" rims. I had some with 3x98 bolt pattern but they were to wide (5 inch) and stretched the tires too much. I found that some Peugeot 205 had as spare wheel an impressive 95/110 R14 mounted on 3 inch wide rims. Now 3 inch may seem too narrow for 145 tires but the beads are very narrow and the tire fits perfectly the 3" rim. Problem : the rims are in 4x108 bolt pattern so I changed the 4 wheels with parts from the 106 and Saxo. I eventually found 4 spare wheels removed the spare tires and mounted the beloved 145/80 R14 Bridgestone Ecopia. For the wheel covers, most don't fit because the rim as an offset in the middle, apparently so the brake calipers fit in the narrow rim. Even though, I have another version of the rim which hasn't this offset. Not talking about the ET here which is ET10 in both cases. So I drilled 4 holes in the rim and threaded them to screw anything I wanted. I choosed nice stock 15" inch covers from the Citroen C3. Look was more a concern than aero but they are actually quite full. I like also the low-profile tire look that is gives.