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Discussion Starter #1
Hi

My 09 Patriot CRD is returning an accurately self-calculated 39mpg average, from mixed driving over the last 4 months.

It's definitely dropped over the last month or so, from being more like 41 mpg.

A few questions:

Q1: how does this performance fit? Is it about right for a Jeep of this age/engine size?

Q2: any thoughts on why it has dropped like this? The type of driving has not changed. Can the weather getting a bit cooler really have made that much of a difference or should I look for the cause elsewhere?

Q3: what is the best way to improve mpg in general? I'm not talking about changing driving style, I'm talking mechanically etc

Q4: I've heard people talk about 'remapping' the engine to improve economy. Is this something that is possible, realistic and worth the investment?

Cheers,

Si
 

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Remapping will cost about £400 ( thats a lot of diesel ) My CRD would do anything between 35---50 mpg .

I must be honest I just filled it up & drove .....I really never got it down to the last 2mpg ---I couldnt be arsed & lifes too short !!


Maybe a 4x4 Fiat Panda would suit your Economy needs better .....& yes the colder the weather ..the worse your economy , but not by anything worth worrying about !!
 

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i thought it was the other way around?
the colder the intake air, the more power available?
if not, then why have intercoolers? or cold air intakes?
To gain the maximum amount of energy output from a given amount of fuel, it must be burnt efficiently i.e. with the correct proportion of oxygen. If you want to burn more fuel, you need more oxygen. There are several ways of doing this, including using nitrous oxide gas, using a larger swept volume, or compressing the air before it enters the cylinder. One side effect of compressing air is that, due to the effect of entropy, it raises the temperature which causes the air to be less dense, but this can be countered by cooling the air once compressed.

However, this has nothing to do with cold weather fuel economy. Cold starting uses more battery power, which must be replenished by the engine. Leaving the car idling while you clear the glass burns fuel. The engine takes longer to get to it's optimum working temperature, using more fuel in the process. Driving with your lights on, as commuters have to at this time of year, uses more fuel. Then there is the thorny issue of winter fuel - do the fuel companies add stuff to the fuel to improve it's other qualities in cold weather at the expense of its combustibility?
 

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Nice explaination Joep .......Top marks !!
 

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...
I must be honest I just filled it up & drove .....I really never got it down to the last 2mpg ---I couldnt be arsed & lifes too short !!
...
I do a long, boring commute, and have had ample opportunity to calculate mpg and price per journey to some degree of accuracy. If nothing else, the mental arithmetic helps keep me awake whilst I endure the tedium of travelling around Loch Lomond.

Anyway, I now only fill up at Shell or Esso garages, having repeatedly proved to myself that I get 5-10% better mpg from them than I do from supermarket fuel.
 

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Discussion Starter #8
Cheers all. Even 'cheers' for the suggestion of the Panda... which I won't be taking up.

Basically, I do a lot of miles, so any gain in economy is important. Simples. I'm not sure that a £400 remap is a good call though, as it does equate to a lot of diesel, but does anyone know what sort of improvement to mpg a remap generally gives?
 

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I've had my Pat a couple of months now and the mpg matches Si's.
I saw a lot of Panda 4x4s in the Italian Alps when I was there skiing. They do the business! Fiat is now the majority owner of Chrysler so maybe a Panda Patriot is on the cards!
 

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I've had my Pat a couple of months now and the mpg matches Si's.
I saw a lot of Panda 4x4s in the Italian Alps when I was there skiing. They do the business! Fiat is now the majority owner of Chrysler so maybe a Panda Patriot is on the cards!
i agree on the pandas,but they are another class.
you can't compare those to the patriots.
 

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Also, your driving pattern may be the same, but you may have sat in a longer traffic queue then normal, or took a little longer finding a parking spot one day. There are always normal reasons for small mpg fluctuations.
 

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Hi new here. I a reading through your mpg figures. I'm a new Pat owner (2weeks) and are completely addicted to her. I've been watching the fuel and as far as I have calculated am only getting 33 to the gallon? Any ideals?
 
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