Regular gas

[xrayguy32]

Will the smart car run on Regular is bad for the car? Thanks for you help!

[pdboilermaker]

No problem, mileage does not suffer. The issue with the hi-octane is simple. As with all hi performance engines (can you belive that hi performace engine in a smart car) the compression is high.

If you have a low compression engine, you can use lower octane gas with no problem, but, take that same engine and mill the heads, put in a long travel crank, a high dome piston etc and it increases the compression.

When the compression is higher, you need to run a higher octane gas so that it EXPLODES with the spark from the plug, not to early due to getting compressed and then heated (like a diesel).

Bottom line is, with lower octane gas in this engine, you may, and that is a may due to computerized controls experience lower performance and/or "spark knock". You will NOT have lower mileage.

[Wdhitch]

I don't know much about engines but I know that if I fill up my smart with regular gas my mileage drops about 4-5 mpg... I've only done it twice and both times it happened.... Seriously though.. you're talking about what 20 cents a gallon at the most??? Just put the premium in it...

[astuto]

When I use regular I always get a 20% drop in milage(low 40's to low 30's) and engine knock. Since premium is less than 10% higher, its cheaper to use premium.

[MPrice2984]

US model Mitsubishi's with 10:1 compression ratios (like US smarts) specify mid grade (89) octane gas. My local Mitsubishi service manager told me running premium is a waste of money unless you have 10.5:1 compression or higher OR a turbo engine. I've been running mid-grade for the last few weeks and am getting between 41-45mpg which is what I got on premium.

[msjohnson1974]

This topic has been completely beat to death in other threads and there is no consensus as many have very strong opinions here. For the extra cost for an entire tank of gas (between 1.60 and 2.40 depending on the differential between the two grades) I'm going to put in premium like the book says to. Its less than a cup of coffee at Starbucks and you still spend less in gas than most other vehicles running regular.

[orangecones3]

exactly what msjohnson said... use what the book says, its only about a $1.50 per fill-up more...not going to break the bank.

[Smart_Dude]

Running premium fuel as opposed to regular grade raises the cost of day-to-day ownership a whopping.... 1/2 cent per mile - that's it! Am I willing to pay 1/2 cent per mile for:
A) Better acceleration
B) Smoother idle
C) Less 'stressed' engine management
D) A liitle better mileage (yes, it's true)
E) Overall general peace of mind

Darned right I am! Besides, you get the added benefit of always watching the OTHER people's faces as you fill your tank with premium for about half of what they pay to fill their's with regular. To coin a phrase... Priceless!

Cheers,
Jeff

[MrJack]

I did a 2000 mile test on my 2008 Passion Coupe, 4 tanks running 92 octane and 4 tanks running 87 octane. I got significantly better mileage with premium (41.0 mpg) than with regular grade gasoline (36.8 mpg). The mileage was enough better with premium that, even with the higher cost of premium, I got a slightly lower cost per mile with premium ($0.10) than with regular grade gasoline ($0.11).

MrJack

[chieftmc]

Originally Posted by MrJack

I did a 2000 mile test on my 2008 Passion Coupe, 4 tanks running 92 octane and 4 tanks running 87 octane. I got significantly better mileage with premium (41.0 mpg) than with regular grade gasoline (36.8 mpg). The mileage was enough better with premium that, even with the higher cost of premium, I got a slightly lower cost per mile with premium ($0.10) than with regular grade gasoline ($0.11).

MrJack

And once again, common sense rules !