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Pordave

OBC accuracy on mpg?

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Over the last weekend I did 371 miles over varied roads with about 220 being on motorways at motorway speeds.

My OBC reset at the start has an average of 36.4mpg.
I think average speed shown was about 46.

This is pretty impressive if true for a1999 2.7 with 138,000+ on the clock.

i know to do an accurate check I need to do brim to brim.

Does anybody get close, or more likely couldn’t care less.

Dave

 

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I've had around 38-40 shown on a very quiet motorway after filling up and resetting the OBC - this was on x-mas day (I used to work for the NHS), so you can imagine there was next to 0 cars on the motorway! 

Mine is a 2.5 2000.

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1 hour ago, Pordave said:

Over the last weekend I did 371 miles over varied roads with about 220 being on motorways at motorway speeds.

My OBC reset at the start has an average of 36.4mpg.
I think average speed shown was about 46.

This is pretty impressive if true for a1999 2.7 with 138,000+ on the clock.

i know to do an accurate check I need to do brim to brim.

Does anybody get close, or more likely couldn’t care less.

Dave

 

I have a 2000 2.7 that returns very similar numbers. They are not over stressed pottering along at 50-80mph in higher gears. They are aerodynamic and light, too

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Adding to this - I did 300 miles today, about 20% country roads the rest dual carriageway or motorway and averaged 36.7mpg. Mightily impressed as my average speed was 69mph. 
 

2003 2.7 

Edited by Apollo000

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I can get 42mpg on a 41 mile motorway commute sitting at 65-70.

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4 minutes ago, Scubaregs said:

I can get 42mpg on a 41 mile motorway commute sitting at 65-70.

And similar on a sprited run.

  • Haha 2

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49 minutes ago, K.I.T.T. said:

And similar on a sprited run.

Is that when using a carbonated soft drink as fuel?

 

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57 minutes ago, K.I.T.T. said:

And similar on a sprited run.

I've seen seen spirited runs get as good as 13mpg in the past 🤔

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1 hour ago, Scubaregs said:

I can get 42mpg on a 41 mile motorway commute sitting at 65-70.

I manage just south of 40 in my .2  I would have thought yours would be more economical that that.

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According to Mrs Araf .2 is about your average.🤣

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4 minutes ago, Araf said:

I manage just south of 40 in my .2  I would have thought yours would be more economical that that.

A straight motorway run can see upwards of 45mpg it’s the rural roads that kill the economy.

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49 minutes ago, Scubaregs said:

According to Mrs Araf .2 is about your average.🤣

After 34 years of marriage, she's lucky to get the opportunity to score me. :) 

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2 hours ago, Araf said:

After 34 years of marriage, she's lucky to get the opportunity to score me. :) 

Mmmmm........lol.

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So my OBC reading about 26mpg on my 3.2 means I'm doing lots of spirited driving....?  It sounds so nice above 3000 rpm though.

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My 3.2 isnt brilliant, I can get it no higher than 30 (displayed not measured) no matter what I do, sits at around 24 in mixed driving.

The 2.7 was significantly better, saw more like 35 on a run & would average around 26-28 (again displayed)

I naturally end up scrutinising these things, namely the DTE function & MPG readout to see how they compare. As expected, both functions are pretty inaccurate in this car compared to the modern machinery I calibrate. They are also largely unnecessary imo. Best to rely on just the gauge & odo I find.

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This feels like my second home... trust me,  whatever BOXSTER you got, it’s frugal...compared to this behemoth🤣
 

  • Haha 1

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On 12/25/2019 at 4:05 PM, naim22 said:

My 3.2 isnt brilliant, I can get it no higher than 30 (displayed not measured) no matter what I do, sits at around 24 in mixed driving.

Doesn’t sound right.

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16 hours ago, Mr96er said:

49278281353_4278897a53_b.jpg

This feels like my second home... trust me,  whatever BOXSTER you got, it’s frugal...compared to this behemoth🤣
 

Can second that! AJ133 was a big step forward but you still arent seeing high figures even with one of those. They sound wicked though! 😂

27 minutes ago, Menoporsche said:

Doesn’t sound right.

It's had a MAF change which helped somewhat mainly during open loop fueling conditions (Intake Air Temperature was reading too low on the older sensor), this brought the mixed average up from about 19 to 24. However during steady state (closed loop) driving it seems to be no different. Lambda sensors maybe?

Plugs & Coils are my next job also, though it seems to run pretty well.

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6 hours ago, naim22 said:

Can second that! AJ133 was a big step forward but you still arent seeing high figures even with one of those. They sound wicked though! 😂

It's had a MAF change which helped somewhat mainly during open loop fueling conditions (Intake Air Temperature was reading too low on the older sensor), this brought the mixed average up from about 19 to 24. However during steady state (closed loop) driving it seems to be no different. Lambda sensors maybe?

Plugs & Coils are my next job also, though it seems to run pretty well.

I'll watch this one with interest as my OBC gives around the same reading, maybe 2-3 mpg better if I cruise for a bit but I suspect that around 24-25mpg on A/B roads is all you're going to get in a 3.2, used to be about the same in my 3000 GSI 24v with similar specific output and induction system but no variable valves and a bit heavier.

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I'm generally happy with the figures I'm getting, though I did come from an S6 V10 so it wasn't hard to improve really 

I do plan to put the larger TB and plenum on so would imagine this might dent the mpg a bit, but for the car you get it's well worth it. I'll see what effect the ignition overhaul does but I'm not expecting much. I'd rather not have to do the lambda sensors but I have no way of knowing whether they are duff, it's hard to interpret what the voltages mean coming out of them (they seem to pulse to just under 1V rather than be a straight volts to AFR comparison, compared this with a friends 987 and saw the same behaviour)

Most of the gasoline cars I've owned have struggled to do any better than 30mpg. The exception is the 2.7 986. I was always told the difference was minimal but I'd say it's enough to be a factor if fuel economy was a priority for a new owner.

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22 minutes ago, naim22 said:

The exception is the 2.7 986. I was always told the difference was minimal but I'd say it's enough to be a factor if fuel economy was a priority for a new owner.

Yes, I can get high 30's from my 2.5 driving like miss daisy on a decent run. 

It's probably about half this on average though....... 

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22 hours ago, Menoporsche said:

Doesn’t sound right.

My 2005 3.2 is the same. Can get 30 on a run, but overall average is 24.8

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