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Volvo C70 Fuel and Mileage Questions

35 messages,  Last post on Aug 27, 2007 at 1:33 PM

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What is this discussion about? Volvo C70, Coupe, Convertible

Messages Page 3 of 4

#20 of 35 Re: Gas? [qbrozen] by jeckles

Feb 11, 2007 (11:36 am)

Replying to: qbrozen (Feb 09, 2007 11:08 am)
gbrozen does have a very good point. 20% sounds high until you do the math and realize the annual difference is pretty small, especially if you factor in the lower fuel economy of the cheaper gas. I figure less than $20 per year difference based on 15,000 miles per year.
 
IMHO: Can't imagine putting low octane fuel in a turbo-charged engine, unless it is an emergency.
 
Sure it won't hurt the engine to run cheap gas occasionally, but you probably shouldn't buy a turbo-charged engine if buying premium gas is a problem (emotionally or financially).
 
When you put regular in almost any modern engine, it automatically adjusts to avoid damage. This sounds okay, but it means the engine runs richer (injects more fuel) and retards the spark timing to prevent premature combustion of the fuel (ping). This means less power, and poorer fuel economy. Plus the extra fuel is not always 100% consumed, and could be passed to the catalytic converter. This extra fuel is not good for the catalytic converter, and over time (repeated use of regular in a turbo engine) could cause premature failure of the catalysts.
 
Just my humble $0.02 on the issue.

#21 of 35 Re: Gas? [jeckles] by rschleicher

Feb 12, 2007 (9:42 am)

Replying to: jeckles (Feb 11, 2007 11:36 am)
I'm not sure I'm following all of the assumptions you made in your calcualtion, although I agree with your larger point that it is still not a huge amount of money.
 
Ignoring (to begin with) a possible mileage difference between premium and regular, 15,000 miles/year translates to 750 gallons/year (at 20 mpg), or 517 gallons/year (at 29 mpg) - using the city and highway EPA ratings. Even with only a $0.20 difference between regular and premium (in some areas it is more like $0.25, or even higher), this works out to $103 to $150 per year.
 
I realize that the above simple calculation assumes that the miles/gallon is the same, whether you are using premium or regular. So I guess the crux of the argument lies in whether there is actually a significant loss of miles/gallon in using regular, and if so, how much. I think this will largely depend on driving style, since the energy content of the two grades of gas is more or less identical. If you are a "heavy-footed" driver, then I think there will be more of a mpg impact, since the loss of peak power using regular (due to spark retardation, etc.) will lead to keeping the pedal down longer. But for someone who normally accelerates slowly, my guess is that the mpg penalty will be minimal or non-existent, and there will consequently be greater savings from using regular.
 
In my own case, I think the savings from using regular will be minimal, and my preference will be for obtaining maximum power capability from the engine.
 
I was interested to see that both the people at the dealer, and the owner's manual, "sanctioned" the use of lower octane fuels as being perfectly reasonable. Other cars I've had in the past that could use multiple fuel grades usually took more of attitude of "in an emergency I guess you could get away with using regular, but we really recommend premium".

#22 of 35 Gas by qbrozen

Feb 12, 2007 (10:25 am)

oh, one more small thing I wanted to point out ... if you have a gas card that gives you rebates, as mine does (and if you don't have one, you are passing up on free money, in my opinion), then the difference between premium and regular is actually a bit less.
 
For example, my Hess card gives me 5% back at the pump. My bill is typically ~$350 per month. That is on regular gas. So the actual gas bought is about ~$368. If I was running premium, that would be about ~$441 retail ($73 difference compared to the retail price of regular gas) or ~$419 with my discount ($69 difference compared to my discounted price for regular). So the price difference for premium is reduced from 20% to about 16.5%.

#23 of 35 So How 'Bout Some Numbers by jeckles

Mar 16, 2007 (9:56 am)

Okay owners, time to fess up!
 
What kind of mileage are you seeing with your cars, being a technical person here is what I suggest for posting:
1. Average Mpg Observed after full tank or more of driving
2. Auto or Manual Trans
3. Highway, City, or Mixed Driving
4. Type of Fuel Used (Gas, Diesel, Octane, and for gasoline if it is ethanol enhanced for smog purposes - sticker on pump usually says)
 
FWIW: most reformulated gasolines usually have less energy (btu) per gallon than pure gasoline, just like most lower octane gasolines have less energy per gallon than the high octane grades (see article referenced earlier). Of course the biggest influence on mpg is driving style and amount of stop and go driving...
 
Look forward to seeing some numbers and comparing results!

#24 of 35 Milage by empty1

Mar 18, 2007 (4:27 am)

19 to 20 mpg using premium fuel on combo highway and local driving. About what I expected, its a pretty heavy car.

#25 of 35 Engine Light by rogert1

May 01, 2007 (11:32 am)

A Few weeks back I had my volvo C70 serviced. Aprox 2 weeks later the engine light came on.It went back to the garage and was put on the diagnostic machine , it came up Bank 1,Fuel Rich,front Lambda sensor. It was re-set but the light came on again after about a week. The same reading came up,re set but came on. The sensor was changed, two weeks later it came on again and the same diagnostic reading came up. Has anyone had a problem like this? because its costing a lot of money !. Any ideas much appreciated. Roger

#26 of 35 Re: Engine Light [rogert1] by tom007

May 01, 2007 (2:20 pm)

Replying to: rogert1 (May 01, 2007 11:32 am)
What year C70 is it and won't the warranty cover the repairs and give you a loaner car? How many miles are on car?
 
Hope you get it solved quickly, but seems as if it is a mystery to dealer by your report.Keep us informed as to solution when they find one. Thanks!!
 
Maybe Volvomax can solve it for you also.

#27 of 35 Re: Engine Light [rogert1] by qbrozen

May 02, 2007 (8:07 am)

Replying to: rogert1 (May 01, 2007 11:32 am)
well, i don't know what that is saying exactly, but the first thing I do when the word "rich" comes up in relation to fuel is pull the spark plug and take a look. Has anyone done that during your trips to the dealer?

#28 of 35 engine light by rogert1

May 02, 2007 (8:50 am)

Thanks for the replies.
My c70 is a 2000 model.And the spark plugs have been checked and are fine. They were new at the recent service.
Since the engine light was put out (re set) the car doesn,t start so well ,which may be a clue to someone. Ive also had it suggested that a temperature sender may be at fault.
 The light hasn,t come back on yet (2 days)

#29 of 35 Re: engine light [rogert1] by qbrozen

May 02, 2007 (9:48 am)

Replying to: rogert1 (May 02, 2007 8:50 am)
how long after the recent service did the light come on?
 
where did you have it serviced?
 
the reason I ask is because my volvo (and i hear most are) was VERY sensitive to the type of plugs. Anything other than OEM gave me problems, no matter how high-quality they supposedly were.

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