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Hi all!

I have put on a new set of winter tires on my smart a month ago, just as it was becoming colder and colder. At the front, im running 155/60/r15 (summer tires were 145/65) and at the rear, im running 195/50/r15. I have a big doubt over my fuel consumption, because before i have put on winter tires, i was averaging 5.3-5.5 litres per 100km. Now, it has risen up to 7.7-7.8 litres per 100km. Im driving in my city only, but i dont understand why has the fuel consumption increase so much. Temperatures are around 5-10 degrees celsius, with rare dip below zero. What could be the case here? Thanks in advance
 

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to get an accurate consumption of gas (and mileage) fill it , note the gallons or in your case liters, drive it, when it gets low note the number of miles (Km) and fill again, ..do this several times. the more you record everything the more accurate your findings will be..
it will average out. and when you swap back to your other tires, do this again... and compare..

steveg. 05 S.MANN cabrio.
 

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Discussion Starter #3
to get an accurate consumption of gas (and mileage) fill it , note the gallons or in your case liters, drive it, when it gets low note the number of miles (Km) and fill again, ..do this several times. the more you record everything the more accurate your findings will be..
it will average out. and when you swap back to your other tires, do this again... and compare..

steveg. 05 S.MANN cabrio.
Well the thing is, im doing just that and those are the numbers i got. I threw away the old tires so i cant really compare them again
 

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How much has the temp dropped? That could be a bigger factor than the tires. Cold start-ups, letting the car warm up. The fact that the ECU will allow the engine to run richer while it is warming up. All have an influence...
 

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How much has the temp dropped? That could be a bigger factor than the tires. Cold start-ups, letting the car warm up. The fact that the ECU will allow the engine to run richer while it is warming up. All have an influence...
Well, it was dropping for a couple of weeks, but i only saw the difference when it came down to 10-ish degrees. But then again, it dipped to minus 10 and the consumption remained at 7.7. i also believe it has to do with the temperature, but this much..
 

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Yes, temp drop can also be a factor. Even just a slight width increase can have a negative effect on fuel mileage.
 

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No no no. The cdi should comfortably average 4.5 L/100 km in good weather and in the very worst conditions, 5.5. Tires will slightly affect consumption. The 145/175 combo I had on my first smart (winter tires) would give 3.8 and the 175/195 combo (summer tires) would give 4.0. So a difference of maybe 5%. With consumption above the 5.x range, some other problem exists.

If you are doing 3 km trips, well that could explain it.
 

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i was running 195/50-15's for 6 years doesn't seem to effect economy, i just switched to 155/60-15 & 185/60-15 snows (the rears are 24" diameter) and it seems to help economy (slower engine speed) at 40F i was getting 48-49 mpgs which is a little better that the 195's in colder weather.
 

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Discussion Starter #12
No no no. The cdi should comfortably average 4.5 L/100 km in good weather and in the very worst conditions, 5.5. Tires will slightly affect consumption. The 145/175 combo I had on my first smart (winter tires) would give 3.8 and the 175/195 combo (summer tires) would give 4.0. So a difference of maybe 5%. With consumption above the 5.x range, some other problem exists.

If you are doing 3 km trips, well that could explain it.
Could it be that the car has done 163000km, so the actual age is affecting it?
 

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I doubt it, unless something has worn out. My first cdi had 247,274 km on it when it was destroyed by some idiot in a Pontiac and it got the same fuel consumption at that age as it did when new.
 

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anybody ever change out the wiper stack to one that has cruise control? I have an 2006 diesel Smart Pulse with rear wiper. is there a different cruise control stack for a Smart with a rear window wiper? are all the cruise control stack the same for coupes, with/without rear window wiper...
thx in advance
 

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Different version....you will need someone with the Mercedes computer to initiate CC using STAR unless you are after the inferior Mr Dot Com version.
 
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