Premium or Regular Gas ?

No. The 'person' is right. The engine has a 'Knock Sensor'. What might be called a pinking sensor, which advances or retards the ignition timing to suit the grade of fuel being used. In effect the ECU 'learns' the best ignition setting. Mike.

I can't imagine why it would require premium. It is a rebadged and mildly reworked midsize European model Ford. You might get an immeasurable performance increase, but it truly would be trivial.

Nice car with a great look, but it is a Ford

Your car is designed for premium fuel due to higher compression ratio. Stick with premium fuel.

Yes, car computer can retard the timing for lower octane, but fuel economy will suffer. You can try the mid grade to see if you get the same mileage... but not regular.

Don't agree

Because you don't know.

I do agree. There's no reason in the world why the engineers would specify a more expensive fuel if it wasn't better for an engine. Sure, regular will run but you may suffer consequences that you will not see and may not immediately comprehend.

What's the engine's compression ratio? If 10:1 or higher I'd used Premium, perhaps cheat a bit with mid grade in cool weather, but not hot weather. Higher ambient temperatures bring an engine that much closer to pinging so premium is needed then to prevent that pre-ignition.

Sorry, I do know. For a high performance car I would agree. KX8 = premium.

It's 10.5:1, so on the borderline. 227hp out of 3 liters.

You could safely run either. "-->> T.G. Lambach

If you use regular the knock sensor will retard timing to prevent engine damage. This will result in less power/mileage. You may not notice it however, unless you drive the car hard.

Vito

I'M WITH TOM on this topic.

US Premium gas is about on par with Euroland/UK regular unleaded. Or in other words your regular wouldn't pass the UK/Euroland acceptance test (not gov). However having said that you will find that the engine control system ECU will compensate for any type of crap fuel that will actually allow the engine to run but the quality of the gas does play a part in the power output and as I said the US lower quality gas is rather low quality and your high grade is about the same as our cheaper grade. Anyway, you pays your money and takes your choice.

Why didn't you buy a BMW?

Sir Hugh of Bognor

The difference between men and boys is the price of their toys. Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK

As one who designed engines for many years, my take on it is to use the lowest octane you can that does not knock. I run plus in my E320 and C280. Regular makes them both knock during acceleration. Knocking is more prevalent during periods of high load (ie acceleration or very high speed) and when the engine is hot (ie summertime). Any effects on mileage are generally negligible.

EJ > If you use regular the knock sensor will retard timing to prevent engine

Hugh, U.S. premium is 93 (R+M)/2 octane which = 98 RON.

So your UK/Euro premium is better than 98 RON? Or are you confusing sea level U.S. 93 premium with the U.S. 89~91 used in high altitude areas?

Tom K.

He'll get right back to you on that, once he finds someone who actually knows the answer ;-)

/daytripper '00 s4 6spd

Compliments of Wikipedia, he seems to have it backwards:

Our regular is 89, so 94-95 RON. UK regular is 91 RON. 87 can be found at bargain places, but not easily, at least where I live.

The computer can retard the timing to deal with the lower grade of fuel. Having said that, it is not possible to retard the timing AND retain the performance. There must be a trade off. Is the trade off noticable to him, or you? Maybe not, and therefore regular fuel should be okay. But, there is certainly something lost by retarding the ignition timing.

Personally, I would run a minimum of 3 full tanks of gas doing your normal kind of driving, and 5 tanks is better. Average the consumption then switch to the other grade of fuel and run the test again. I suspect that premium fuel will indeed give better mileage. Divide the fuel cost by the mileage yielded to arrive at the cost per mile. You may find that the cost per mile is actually lower with the expensive grade of fuel. In my area, premium fuel typically costs $0.20 more than regular, so if regular costs 2.30, then premium will cost 2.50. If the mileage is 22 on regular and 25 on premium, then regular costs 0.1045 per mile, but premium costs $0.1000. Premium is cheaper in this example. In 10,000 miles, you'll save $45, and have a bit more pep.

Jeff,

I have been following the thread since my original post. I like your suggestion and will try it.

Double Tap

Tom

I admit that its only 5 years since I was last over there but I can remember having a chat with my ex-wife's uncle who was a director of Conoco and his neighbor was on the petroleum side and told me that. I also get it from some of the car mags over here (UK) so it could be a bit of 2+2=5.

However, my friends Corvette (I think its a 93) does run better on 98 than on regular (premium) Its a bit like McDonalds where small starts at medium - medium = large and large = weight watchers phone number please.

Sir Hugh of Bognor

The difference between men and boys is the price of their toys. Intelligence is not knowing the answer but knowing where and how to find it!

Hugh Gundersen snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK

Okay, and from where do you get the info that leads you to your decisions if you do know?