Super unleaded - does it make a difference?

[JonMad]

Hi,

Specifically on my '03 W209 CLK55, will I notice any difference if I go for super unleaded? If so, does it take a few miles for things to recalibrate to it, or is it pretty instant if the tank was near empty of normal uneladed?

Cheers,
Jon

 

[Adam230K]

Its more noticeable on forced induction engines.

Try it for yourself, do a full tank of super and normal unleaded and see how many miles you get each time without changing your driving habits too much.

 

[JonMad]

Thanks Adam - early days with the car at the moment as I've only had it a couple of weeks. Won't take long to get through a few tanks worth though, at about 300 miles range from what I can tell so far. I was more thinking about possible performance gain than economy though, but thanks for that thought too.

Cheers,
Jon

 

[Adam230K]

Thanks Adam - early days with the car at the moment as I've only had it a couple of weeks. Won't take long to get through a few tanks worth though, at about 300 miles range from what I can tell so far. I was more thinking about possible performance gain than economy though, but thanks for that thought too.

Cheers,
Jon

On the economy front its very hard to notice... i might go as far as saying that in road going standard cars (ie. not 500bhp turbo charged beasts) you will probably not notice anything. Your mind will tell you it feels quicker and at times i though that with super my car picks up a bit stronger lower down in the rev range, but i'm sure its all relative.

 

[andy_k]

yes you'll notice a difference

 

[lynall]

Years ago my father in law ran a mighty powerful nissan sunny 1.3 he tried the super unleaded and said yes it did make a difference to the power! and better economy but the cost difference versus mpg wasnt enough to justify it.

Ive tried it in several cars and never noticed any difference.



Lynall

 

[GrahamC230K]

yes you'll notice a difference

but will there actually be one?

I never could tell a difference in the C230K. Worth trying though.

Never use anything other in the S4.

 

[njkmr]

I used to put Super unleaded in my Subaru WR1 when I had it .

I thought it did make a difference to be honest .Its hard to describe but it gave it a meatier blast when accelerating .Felt less tinny ,but as I say its hard to describe .

 

[davidbilyk]

Have a little read on here.

Octane rating: Information from Answers.com

 

[R2D2]

Fifth gear and Which both did tests and the super made quite a difference on some cars. about 10% bhp in some cases. When i've used it I say it made a slight difference.

 

[JonMad]

Your mind will tell you it feels quicker.

heh heh, you could be right there. I haven't really noticed anything on previous cars, but they've all been older. If it's sunny on Saturday I'm thinking of heading up to Santa Pod, so will try and put some super in before that. Hope that hasn't cursed the weekend weather!

 

[Buggerlugs]

It works for me. My daily runaround is a Rover 75 2.0L V6, on regular it's very noticeably underpowered, they're all the same, so I use super which makes the car much more driveable. I've compared the fuels back to back on cars and bikes and yes, it does make a noticeable difference, whether it makes 6p/litre difference though........

 

[amwebby]

"A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power."

 

[ray_hennig]

I don't think so ...

I use 98 in our old Renault 5 because 95 causes it to pink slightly after I adjusted timing for better running. My adjustments also greatly improved MPG so, for a 1987 Renault 5, yes.

For my 300CE-24, no, it makes little or no difference. Once, I got less MPG from Tesco 99 than from Total 95 although there's no evidence to say it was because of the fuel - probably different driving conditions.

Porsche made a statement a few years ago saying their cars were all designed to run on 95 so any extra octane is just wasting money.

That's the situation as I understand it.

RayH

 

[amwebby]

If your car is set up for higher octane, i.e. high compression or advanced timing, then using a lower octane will degrade performance.

 

[Bobby Dazzler]

"A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power."

The key here is the octane rating the engine was designed for.

An engine which cannot advance/retard timing will not produce more power using super than it would with regular, unless the timing is adjusted manually.

However if a car is designed to adjust timing in real time so that it's always operating at 'the limit', ie retarded a touch from the point at which knocking is detected, then it will produce more power with super than regular as advancing timing leads to increased power.

It's a similar principle to ABS really, ie adjusting braking force do it's at the limit of when the wheel locks.

 

[mattc]

The key here is the octane rating the engine was designed for.

An engine which cannot advance/retard timing will not produce more power using super than it would with regular, unless the timing is adjusted manually.

So which are the earliest mercs that can do that? 124's, 126's? Presumably it needs some form of electronic management that can detect the difference and adjust accordingly?

 

[jaymanek]

makes no difference on older cars.. i dont think it makes a huge difference on newer cars either... all depends what is required when it leaves the factory. Just put in what it says on your fuel fillter cap or car manual.

Super Unleaded is another one of those things like fuel saving magnets.. all in the head most of the time.

 

[Swozza]

My experience and its limited.

I do think they is a slight increase in power but without testing it correctly it may all be in my head. However the main difference for me is when I use regular the emission light comes on about every 50 miles (Its been checked out and the reading is bogus), however using v-power or BP-Ulit and it doesn't.

Swoz

 

[Charlie W]

Ive used 98 whenever i can...ive used my 200te w124 for a year now, and i have now become convinced that it degrades the performance...sometimes the engine feels gutless, empty, and looses steam, especially when climbing hills.
This doenst happen when i use 95...I imagine the engine does not like the 98 for whatever reason...timing by what ive read?...and as a result doenst work well.
Funnily, similar effects are felt when using S mode or E mode...when i am on my own in the car, s mode works just fine...but when i have weight in the car, even a couple of heavy bags in the boot, i feel it whimpering...with E I feel the car is stronger, especially when fullly laden: ive had a full car, five ppl, suitcases, home sound system, and a fridge...was all stuff worth a week and the estate swallowed the whole lot...and still looked fantastic..in fact i think it may have looked better; the laden suspension demonstartes what the car was designed for, autobahn lugging...ha