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What is the downside of using regular unleaded gas with 10% ethanol in my 2009 Smart 2for passion ?
 

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Possible lower mpg’s and the threat of destructive engine ping . For the few pennies per gal difference , it’s not worth the risk .
 

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You can use it in a pinch -- I've been in places so rural the populace hasn't heard of Premium (91+) -- but do not use it often. While the computer can change timing for incorrect fuels, it's not perfect at it. Extended usage of Regular (87) can lead to carbon build-up, detonation, and potentially, burned valves.

Some people have only ever used Regular in their smarts and report no issues. Meanwhile, others have been less lucky. Honestly, I don't think it's worth taking the chance on just to save a few dollars at the pump.
 

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This Pros/Cons “regular vs. premium” thread is old (2010) but still relevant - especially Post #8.


At the end of the day, it’s beyond warranty, it’s your smart but please don’t post your anger towards smart if/when your daily driver self destructs!
 

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Mercedes makes no money on saying that premium fuel should be used. In fact they probably lose money and customers when a potential owner sees that. So why do they indicate its use - because the designers of the engine probably know a little more than the "guy on the street." Once you own the car though, if you want to take that chance, it's certainly your call. In probably a few thousand fill ups, you will probably save enough to pay for the new used engine it will need. :)

Len
 

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Great article! I didn't know this before, but it completely explains why I destroyed the engines in 2 lawn mowers about 1/2 way around the house on the first mow of the season. Two different years, of course.

Since then, I drain the fuel out of all of my gas engines if they aren't going to be used in a month or so and I've upgraded my riding mower to one of those Ryobi RM480 battery powered riding mower.
 

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What higher octane gas does is lower the combustion temperature cycle, thereby lessening the spark knock.

Conversely, the raised temp can also lessen plug and valve life.

Engines designed to run regular are built to tolerate the heat cycle, and some actually need it for proper operation.

S u b R o s a
 

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I used it regular unleaded once. We had a smart car event in Iowa. That’s all they offered there. Didn’t notice a difference. Drove over 235 miles on the highway back home.

Another time, I filled the car up with 93 octane. Got the best fuel economy ever. Not worth the extra price of the fuel.
 

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There's a reason that premium gas is recommended, for sure. now more than ever, you probably want to use it, to offset the ethanol content. Interesting article on it here. I was unaware of some of the particulars myself. So much for long term storage of such gas...

The problem with ethanol in gasoline - The Globe and Mail
I'd like to know that article's source, because many of the issues they bring up were solved a couple of decades ago.

Modern engines and modern fuel systems are built to handle ethanol. Further, depending on where you live, buying Premium doesn't save you from ethanol content. Where I'm at it's 10% across the board.

Ethanol is indeed bad for lawn mowers, carburetors, old motorcycles, and old cars. But it's a non-issue for a modern car. The biggest impact a modern car should see from ethanol is maybe a small decrease in mpg.

And if you need to store fuel for a long time, throw some stabilizer in the container.
 

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The high octane rating has a lot to do with the high compression ratio of the engine.
My smart isn’t the only car I have that requires premium fuel my rx8 does too.
Yes the pcm can adjust for it but the damage the lower octane fuel can cause damage over time.
The smart is my third vehicle that requires premium fuel as my 03 Escalade I had required it too(it could run on regular but I could tell a performance difference when I used premium fuel just like I do in my rx8 when I use premium)
 

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It’s funny, I own 2 cars that require the use of premium fuel. The smart car, and Fiat 500. The Honda Fit uses regular, and achieves better fuel economy. Then both of those smaller cars. The Fit with it‘s CVT transmission, 130hp engine. Honda alway been good in squeezing the best fuel economy, out of their power plants.

 

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Smark it has a lot to do with the gearing.
Most don’t realize that.
A car can have a different ratio then another which can effect that.
For example my Miata has a final drive of 4.30:1 whereas my rx8 has a 4.77:1(the 8 is geared like that to take advantage of the engine)
 

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How many miles on your ride? I changed the plugs. Put a K&N air filter in place of the stock because the engine had a hiccup. Svr writer told me to run a tank of 87oct for one tankful. I didn't have problems after that. Between 2 451s and 3 453s I vary the gas once in a while. If I have 2 pips on the gauge with 93 non oxy, I can get away with E15 88oct once in a blue moon.
 

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Smark it has a lot to do with the gearing.
Most don’t realize that.
A car can have a different ratio then another which can effect that.
For example my Miata has a final drive of 4.30:1 whereas my rx8 has a 4.77:1(the 8 is geared like that to take advantage of the engine)
‘The CVT Honda Fit, Achieves better fuel economy. Then a six speed manual transmission one. I‘m surprise, smart didn’t equipped the 453 with a CVT transmission. Instead of the dual clutch.
 

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True but most don’t like the cvt transmission.
Actually I seen where the cvt isn’t as good as a properly geared manual transmission.
One thing is a cvt uses a torque converter like a regular automatic.
My main problem with it (cvt) is it either keeps the engine wound up near redline or you have no power(had a Dodge Caliber as a loaner) but the fuel economy was ok for the vehicle’s size.
Smart could’ve used it but keep in mind that’s a Nissan tech but if they would’ve allowed them to use it I don’t know(plus customer feedback also makes the difference on the transmission used in a particular vehicle)
 

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True but most don’t like the cvt transmission.
Actually I seen where the cvt isn’t as good as a properly geared manual transmission.
One thing is a cvt uses a torque converter like a regular automatic.
My main problem with it (cvt) is it either keeps the engine wound up near redline or you have no power(had a Dodge Caliber as a loaner) but the fuel economy was ok for the vehicle’s size.
Smart could’ve used it but keep in mind that’s a Nissan tech but if they would’ve allowed them to use it I don’t know(plus customer feedback also makes the difference on the transmission used in a particular vehicle)
Honda, CVT don’t use a torque Converter. the CVT transmission in the Honda uses a wet clutch similar to that found in a standard automatic transmission. While stopped the clutches are all released and there is no transmission of power to the output and CVT belt. To reduce/remove hard shifting the engine power passes through a torque dampener, then to the CVT input shaft. Once throttle speed comes up the drive clutch is energized and begins to apply the clutch locking the engine input to the CVT input shaft. For forward gears there is a clutch that is applied for direct drive to lock the input shaft to the CVT input pulley and belt.

What I like about the CVT‘s, in our 2015 Fit, and 2018, Accord Touring. Both are equipped, with paddle shifters. If put in sport mode. They simulate gearshifting. If pushed hard on the highway, the Fits CVT, can be obnoxious. 40 mpg, using regular fuel is nothing bad to talk about. Honda moved away from true automatics, and manual Transmissions. To CVT’s

We also rented a Dodge caliber, when one of our cars was in the body shop. It was a horrible CVT transmission. Noisy strange power band. CVT’s have come a long way now, since then.
 

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I agree with you on the noise in the caliber.
They used a Nissan cvt in it which even under its own brand it’s a star for reliability.
I didn’t know Honda didn’t use a torque converter in the cvt they have(which is new to me)
 
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