Shell V Power Diesel consumption

[FabiaTom]

I have only had the car for 4 tanks full of fuel. Its a 2006 71k MK1 Fabia vRS with an Awesome remap. I'd like to share what I have noticed with regards to the fuel used.

Tank 1 = Shell fuel save diesel - 500 miles to that tank before the light came on.

Tank 2 = Shell fuel save diesel - 530 miles to that tank before the light came on.

Tank 3 = Shell V Power diesel - 360 miles to that tank before the light came on.

Tank 4 = Shell V Power diesel - 340 miles to that tank before the light came on.

Obviously there are factors which effect the consumption. I have done the same journey 6 days per week which includes 60-70mph country road driving and stop start crawling in traffic.

The only significant change was on tank 4 when I took myself, my partner and my son to the coast for the day driving at average motorway speeds. 120 mile round trip.

Forgive me if there is a similar post (I have searched) but has anybody else out there noticed such an increase in fuel consumption using a performance fuel?

The use of the V Power is noticably better to drive (more responsive, smoother, dare I say increases performance) but is this really worth the 150+ miles difference per tank load for the average daily commuter!

[@Lee]

less motoring for more money? I'll not have some of that.

[Trev.]

I only use v power once a month! Dont really feel any difference!

I did in my wrx or my skyline but not my fabia so only use it when i want to cleab out the injectors etc!

[booke23]

I experimented with V power in my Octavia a while back. I used it for 2000 miles.

I experienced a slight reduction in MPG and no noticeable difference in power. I did notice the car was much less smoky when booting it though...especially noticeable at night. So It does seem to be a cleaner fuel but on balance, definitely not worth the extra cost in my opinion.

Edited 12 November, 2012 by booke23

[XLBaconDoubleCheese]

I'd put my money on the drop being about the time the temperature dropped.

[wilsy7]

I'd put my money on the drop being about the time the temperature dropped.

Ditto, I've noticed that big time

[Trev.]

^{My mpg hasnt changed with the temperature, engines run better at cold temperature, Hence COLD air feeds to your intake, so the temperature should increase the mpg.}

^{Think about it....}

[VRSD30]

Yes cold air is more dense so it needs more fuel in order to burn efficiently, I have noticed a drop in mpg as the temperatures have fallen, even though it's being driven the same. Now getting around 47-52mpg instead of 55mpg +

[booke23]

^{My mpg hasnt changed with the temperature, engines run better at cold temperature, Hence COLD air feeds to your intake, so the temperature should increase the mpg.}

In theory that's true. Cold air = Denser air hence more air drawn in per stroke.

But in a turbo charged car the boost is regulated, so it doesn't really matter what the air density is....boost pressure will be the same.

Intercooling will be more efficient, but this only has a small effect, and is far outweighed by a number of factors ie, Engine taking much longer to reach operating temperature, High electrical load, (heated seats, rear window, mirrors) driving conditions, (wet roads give you less MPG) and winter diesel addidives.

All this adds up to give you less MPG in the winter. In my experience, it's especially noticeable when the temp is below about 10 degrees C.

[trebormint]

In theory that's true. Cold air = Denser air hence more air drawn in per stroke.

But in a turbo charged car the boost is regulated, so it doesn't really matter what the air density is....boost pressure will be the same.

Intercooling will be more efficient, but this only has a small effect, and is far outweighed by a number of factors ie, Engine taking much longer to reach operating temperature, High electrical load, (heated seats, rear window, mirrors) driving conditions, (wet roads give you less MPG) and winter diesel addidives.

All this adds up to give you less MPG in the winter. In my experience, it's especially noticeable when the temp is below about 10 degrees C.

That doesn't make sense to me. air density is dependent on boost pressure as well as temperature.

Yes, the turbo will heat up the air as its being pressurised, but if you start off with a lower input air temp, the output temp will be lower.

Also intercooling makes a huge difference, especially on high boost or constant boost, in reducing the inlet temperature of air into the engine.

[XLBaconDoubleCheese]

So cars are MORE economical when they are running cold?

[VRSD30]

I've been using the Esso 'we fuel pregress' diesel for the last 3 weeks, definitely less soot builds up on the tailpipe, MPG varies with the outside air temp imo especially heavy consumption before the engine warms up during the cold mornings of late. Cheaper than V Power and Optimax as well.

[XLBaconDoubleCheese]

I'm no expert but, this is how I understand it. . .

Car engines are designed to run at a certain temperature. So the Fabias is around 90c. At this temperature the engine returns the best mpg. When it's cold, the oil is thick & the engine is tight, I think it over fuels slightly too. This means you use lots more fuel during the warm up process.

So, my drive to work is 30min. In the summer my car is up to temp within 10 min. In the winter it just about get up to temp as I'm nearing the end of my trip, thus greatly increasing the amount of fuel I use.

I know cold air intakes make the car slightly more powerful, possibly slightly more economical too, but the above will far outweigh any gains from that point of view.

So what bits have I got wrong? And more importantly why does my car, and the million posters moaning they are using fuel each winter do so?

[Trev.]

I'm no expert but, this is how I understand it. . .

Car engines are designed to run at a certain temperature. So the Fabias is around 90c. At this temperature the engine returns the best mpg. When it's cold, the oil is thick & the engine is tight, I think it over fuels slightly too. This means you use lots more fuel during the warm up process.

So, my drive to work is 30min. In the summer my car is up to temp within 10 min. In the winter it just about get up to temp as I'm nearing the end of my trip, thus greatly increasing the amount of fuel I use.

I know cold air intakes make the car slightly more powerful, possibly slightly more economical too, but the above will far outweigh any gains from that point of view.

So what bits have I got wrong? And more importantly why does my car, and the million posters moaning they are using fuel each winter do so?

LOL You must drive like miss daisy for your car to take 30mins of Driving to warm up! Mines takes 10 mins no matter what the outside temperature!

[Trev.]

But also, the temperatures have been under 10c for the past 3 weeks where i am, there has not been that much of a drop in temperature for you to say that its only the temperature thats causing the op to lose 170miles of fuel from tank 2 to tank 3?!?! Even during the height of summer the temperatures where i am only reached 15c. i coudl admit it to be only temperature related if it was a 20c drop but not 5-10.

[chris69]

A very interesting thread, i have used VPower but not noticed much difference in running or economy tbh.

I do think it will be the time it takes for the engine to get upto its optimum running temp that makes economy worse in the winter.

I havn't had my fabia long enough to really compare just loving the economy/performance compared to my last petrol car lol

edit- is it maybe to do with your remap? i have a remap on mine but they all differ...

Edited 13 November, 2012 by chris69

[XLBaconDoubleCheese]

Oh yeah, it wouldn't account for all of it for sure. Was just a thought that could contribute to it. I never said it would be the ONLY reason did I?

Amyway, Sooooo, which bits wrong in what I said? I missed that bit in your replies of you telling me how slow I drive. 20min to warm a diesel car up properly in cold weather seems normal to me. I'm talking proper warm not just water temps up a bit.

I don't claim to be any kind of expert, hence my request for someone to point out where I'm wrong.

[wilsy7]

LOL You must drive like miss daisy for your car to take 30mins of Driving to warm up! Mines takes 10 mins no matter what the outside temperature!

I presume he was referring to oil temp and not water temp.

Basically what it boils down to is, diesels don't return optimum mpg until at full operating temperatures. Which during the winter takes longer. Simple

[Trev.]

Oh yeah, it wouldn't account for all of it for sure. Was just a thought that could contribute to it. I never said it would be the ONLY reason did I?

Amyway, Sooooo, which bits wrong in what I said? I missed that bit in your replies of you telling me how slow I drive. 20min to warm a diesel car up properly in cold weather seems normal to me. I'm talking proper warm not just water temps up a bit.

I don't claim to be any kind of expert, hence my request for someone to point out where I'm wrong.

Can you point out where i said that your were wrong?

I also said that you must drive like miss daisy as my car takes 10mins too warm up, doesnt matter the temperature!

Also in my replies i was implying...as i said...that there is no danger the op can lose 170miles worth of fuel purely down to the temperature drop which is what YOU indicated in the first place (post 5 in the thread).

But now you seem to have retracted that statement in post 17. But to answer your question in your initial post on the matter "I'd put my money on the drop being about the time the temperature dropped." Would imply that you were stating that the only reason for the drop in fuel was temperature.

You obviously dont like being made too look wrong hence why you have tried to initiate an arguement about the matter in your last post where you publicly try and get me to tell you, that you are correct when that was not the original issue. The issues arose with your initial statement, where you were wrong.

But as it turns out you do no how an engine works as you shown in post 13. Which i do not have a problem with. I have not based my comments on any of your other posts other than your original post where you implied something that was wrong.

This is getting pathetic but i hope the op finds his answer and if you have any issues with this reply matt, i ask you pm me as i wont condone arguing on a thread.

Regards

[XLBaconDoubleCheese]

I stand by my original statement, the temps round here recently dropped as did my mpg (for that reason). My gripe was the statement that 'cold temperature should increase your mpg'. I didnt check his local weather so just threw the idea out there that the cold weather could have a detrimental effect on his mpg.

I don't like having words put into my mouth, but its no biggy! Chill, we can all still be friends :love:

[thesquiff]

Yes, mpg was noticeably worse for me to:

http://www.briskoda.net/forums/topic/242774-shell-v-power-diesel-worse-than-fuelsave/page__hl__%20worse%20%20than%20%20fuel%20%20save

[FabiaTom]

That could be the answer to my drop in MPG however as I did state in my opening post that I have only had the car a short amount of time. The car has reached 90 degrees on my way to work around about the same point on my commute ( Give or take 1 mile max ) and within my time of ownership the outside temperature has not changed that much! I do enjoy the up sides to using the fuel but over a full year the cost involved is huge!

Good to see I'm not the only fuel save anorak!

[booke23]

air density is dependent on boost pressure as well as temperature.

You're missing my point. When you put your foot on the throttle the ECU decides what amount of fuel to inject and how much boost it wants from the turbo. It then adjusts the variable vanes to achieve the boost it requires. You don't get more boost when it's cold, you get the same boost because the ECU regulates it. If you plug in VCDS you can monitor all these parameters and see this effect in action.

Yes, the turbo will heat up the air as its being pressurised, but if you start off with a lower input air temp, the output temp will be lower.

You sill get the same boost.....the colder temp at the manifold may have a slight effect on power, but as I said in my first post this is by far outweighed by the other factors I mentioned.

Also intercooling makes a huge difference, especially on high boost or constant boost, in reducing the inlet temperature of air into the engine.

Yes, but you sill get the same boost.....my above sentence equally applies here.

LOL You must drive like miss daisy for your car to take 30mins of Driving to warm up! Mines takes 10 mins no matter what the outside temperature!

I guarantee you, that on a cold morning, your oil temperature is nowhere near up to temperature in 10 mins no matter how you drive it.

Edited 13 November, 2012 by booke23

[MattH]

I couldn't be arsed to read all that lol.

But here is some of my statistics.

On Friday (9/11/12) I drove from Manchester to Essex. According to Apple maps its approx 235miles. I filled up with V-Power @ £1.45.9/L. Total cost was £55 to fill, 37.7L. I got all the way to Essex on around half a tank. While I was there I used the other half a tank pottering around town visiting family and friends.

I came home on Sunday (11/11/12) again filling the tank to the brim. The car wasn't completely empty and the red light wasn't on, iirc the trip was showing around 70miles to next fill.

Again I filled with V-Power, slightly more expensive than last time @ £1.499/L. Total cost to fill was £55, 36.69L.

On my return journey I set the Cruise at around 70mph and took my time to get home. As I say we left on Sunday at around 9pm. We arrived home at 12:20am as there was little to no traffic. I have just over half a tank left.

I downloaded an app that I saw someone post about on here (roadtrip) and it's telling me 358mile trip @ 44.36mpg.

I'm sure I could have accorded better mpg but when it's only cost me £60 to travel 470miles, I'm not complaining lol.

My old car cost £60 to fill and that only got me there, meaning a round trip was £120. That didn't include the use while I was there.

[eric87]

Agreed, people tend to go by water temp but oil temp is the important factor.