451 smart fortwo

Tonight I took my first test drive, and I loved it! The Smart car is a whole lot of fun to drive. I didn't really mess with the manual shifting, because I was nervous, but I had a great ride and I wish it was longer. I liked everything the dealer had to say about the Smart, especially the fact you can change out all the body panels whenever you want. One thing kind of took me by surprise, though. He mentioned they recommend premium fuel. This in my mind kind of defeats the purpose of having a really fuel efficient car.

So my question to you guys is, do you use premium fuel? If so what are the real benefits to using it over regular?

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At the risk of waving a big red flag in a bull pen; ONLY USE PREMIUM GRADE FUELS AS RECOMMENDED BY smart.

I am in Australia. The lowest grade fuel here 91 unleaded. Premium is 95 and some such as Shell V-Power are 98. The price spread is about 10c per litre (3.8 litres per US gallon). You could read that as about 5c per litre difference between 91 and 95 RON... say about 20c a US gallon. In practice I'm paying $1.55 per litre for V-Power, say $5.90 per gallon. And you gripe about US gas prices... don't ask Europeans what they are paying.

The price should not be an issue. The higher performance the engine, the more it is likely to be designed and tuned for high octane fuels. The smart BRABUS has the highest factory tune of the fortwo engines. It is turbo and requires 98 RON minimum... that is not commonly available across Australia; we don't get that engine option. We do get the standard 84 bhp turbo offered. It requires 95 RON. Using a lower rated fuel than manufacturers' spec is foolhardy. I speculate that one reason the USA is not offered the turbo engine is due to lack of faith in consumers using the required fuel grades.

I have a smart pulse (not offered in the USA), with turbo. The car is now a week old and I have driven 1500 km in it (say 900 miles). When new, the fuel was of dubious quality. It had poor gas mileage. As the engine breaks in and after two full tanks of V-Power the performance is improving and the mileage is approaching the advertised. On Sunday, I drove 360 km and it took 30 litres to refill. The trip back that evening (the same 360 km) took 20 litres to refill. 10 litres of 91 fuel costs $14.50. Paying 10c / l extra over 10 litres is one dollar. Yes: using the higher grade fuel does save money at the pump, if an extra dollar saves me $14 worth of gas. And if you really do like to drive fine performance machinery, you may be able to tell the difference in engine noise and smoothness.

My worst mileage was 33 US mpg when the car was new. My current mileage is edging over 43 mpg. And that is a turbo engine. I'm expecting the mileage to reach the rated 4.9 lhk (48 US mpg) quite easily. The smart is a most fuel efficient gas engined non-hybrid car... but you should fuel it with efficient gasolene.

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Interesting. Yeah I agree that most Americans would stick with regular gas even if they specifically said otherwise with a turbo engine. I also find it interesting that the engine has to be broken in. I guess that makes a lot of sense now that I think about it.

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This American won't. I know too much about engines to risk detonation from running a lower-than-recommended octane fuel. Detonation can break the spark plug electrodes, the porcelain around the plug, cause a fracture of the ring lands, and can even cause fracture of valves-intake or exhaust. If the wrong thing breaks, you could be looking at a totaled engine.

The higher the specific output (HP/in3) of the engine, the greater the sensitivity to detonation. An engine that makes over one horsepower per cubic inch (like the smart's), is much more susceptible to damage from detonation than an older, lower specific output engine.

Seriously, how bright would you feel if you saved $1 at each fill-up and then had to pay for a major engine repair caused by detonation? If you can't afford premium fuel for a car that gets 40mpg, then you need to sell the car and put the money towards bus, taxi, and subway fares.

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the smart engine has a relatively low HP/displacement output. the only engine lower would be a geo metro 1 Liter 55HP. if you know you will only drive around town, or keep it below 60mph, 87 octane is fine. i got 44mpg on my last 2 tanks of 87 octane on my smart in stop and go driving.

it depends on your driving habits, if you're a city driver, don't floor it, use 87, if you drive at or above 60mph, use 91+ octane. the smart car is "loafing" when driven below 60mph, the smart will happily go to 91mph (if you get a re-map 130mph)

it's a silly question, if you drive mostly hiway miles, use premium, if you drive city, use regular. the smart isn't nearly close to a "high powered" vehicle, 70 HP at one liter is low today. and i seriously doubt any smart driver will see over 4000rpms when left in "D".

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Hi mr bad, got your ScanGauge yet?

Yep, the NA engine at 71 bhp is a relatively mild tune. The old "rally" rate is 100 bhp per litre.

US pump octanes are somewhat different to Europe and Australia. MON vs RON. Aren't all those different pump octanes obtained by mixing from two storage tanks? That would imply that the pump itself is blending for a nominal octane, so there is a good chance that no two gas stations would give you exactly the same blend?

About this time of year, US winter mix fuels start to appear, depending on when or where they predict the first freeze. How is this done? Additives in the stored gas or premixed in fresh deliveries? ... spin the octane wheel and where she lands, nobody knows.

The 84 bhp turbo engine is a different critter to the NA. Gentle pressure on the accelerator and easing off when it gets over 3,500 will produce smooth and gentle gear changes and acceleration in Auto. Press a little too hard the car takes off. Turbo boost maybe. It flies up to over 5,000 in first gear and hits 60 kph (38 mph) before you know it. I don't know if the NA exhibits this behavour - when it wants to spin out, it will do so and does not Auto shift at the low rate spots.

Refilled today and consumption was up to 6.6 lhk (36 mpg) for the fill. That tank saw a lot of local town trips in stop go traffic and a hill climb to the Tablelands plus some rev head standing starts to break in the engine. Now that I have a better feel for the car (which is getting smoother every day - now over 1800 km) it may be worth dropping the fuel back from V-Power (98 to 100 RON) to normal Premium of 95 RON. With the turbo, I will not go below the recommended 95 RON.

Rumour is that the MHD system will be an offered option on all NA engines in the new year. The turbo is not so easy to turn off because it needs to spin down, cool and be oil fed till it stops, so it may not get the MHD option. MHD can add 30% fuel economy to those stuck on heavy urban roads.

A quick question: my pulse turbo idles at stop at around 930 to 990 rpm, which seems very high, but since the transmission is not creeping the car forward, I guess it's by design. Does the NA idle so high?

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scan gauge is on the top of my list, life keeps happening to me! i had a good job a month ago, a previous employer comes along with a "better job", i take the bait, the better job sucks, the good job is no longer available...

MHD, i'd never have one, letting an engine stop for several minutes, then starts with an immediate load, i won't buy that! the oil drains from the cylinders in 30-60 seconds, then the engine starts, almost DRY, and put under immediate load.

all my cars, on "cold" i let idle 60 seconds before driving, when warm, 30 seconds, the smart has synthetic oil, i let it idle 15 seconds when warm.

as for idle, all the pics of smarts i've seen idle in the 900's, between SG and tach pics... i think my metro might have idled around 850 (no tach) i can live without the turbo option, but would love your tires! i had 195/50-15's on my metro and loved them, the skinny things they put on US smarts are for the birds!

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Where I live the difference between filling up with premium and filling up with the next lower grade is about 90 cents - to me it's certainly worth 90 cents every few weeks to follow the manufacturer's recommendations. - sheureka

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Have you ever experimented with using lower grade fuel? If so how does it affect gas mileage/performance?

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In general you will get more MPGs from premium fuel. So, lets say you will put 8.7 gal of Regular and get 37MPG (322 miles) and lets assume that with 8.7 gal of Premium you will get 42MPG (365 miles). Difference about 25 cents (Regular vs Premium), so you will pay only 2.17 more per tank, but will drive 43 miles more.

Does it really worth for you to mess with your brand new car?

CUBE

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The Smart ECU has a knock sensor. It will reduce engine power as you add low grade fuel. You might think you are saving but then again you are driving a Smart Car and it is hard to fool with. Go with Premium and enjoy the millage and power.

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You can use regular fuel, on a limited basis, if needed. I caught myself very low on gas and pulled into a station right after Hurricane Ike. The pumps were labeled regular, mid-grade and premium - but they were all marked with 87 octane regular - all for the same price! Not having any choice, I filled up. I didn't notice any major differences in performance, but when it was down to a half tank again, I filled up with premium to sort of equalize the octane. . . I plan to run only premium, but know that I can use lower grades if needed, on an emergency basis. It's not worth the few cents or few dollars saved to have lower mileage or risk damage from knocking.

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Yeah, I think it's definitely worth it to stick with the higher octane fuel. I called the smart dealership around me to get a second opinion ( and to get on the orphan list :) ) and the lady I spoke with says Mercedes especially recommends higher quality fuels for their vehicles, but it's not a total necessity. I figure it's worth it because you get more life + possibly more mpg with it.

I wish I knew about this sooner, I may start using it with my Yaris to see how it changes the ride.

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