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Discussion Starter · #1 ·
< ="" ="text/" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">

Hi all, just a thought on fuel consumption, I have recently bought a 1.6sx Lacetti Station Wagon and I'm pretty chuffed with it. But I have noted that there does seem to be a huge variation in MPG posted by various people in previous topics on this and other forums.

Checking the Handbook page (3-4) yields the following information
FUEL RECOMMENDATIONS
Use only unleaded fuel rated at RON 95 or higher
Fuel quality and additives contained in fuel have a significant effect on power output, driveability, and life of the engine.

CAUTION
*Use of fuel with an octane rating number than RON95 may damage engine.
*Use of leaded fuel will damage exhaust system and invalidate the warranty.
This got me thinking about the claims that various fuel companies make about Super Unleaded giving better MPG than Regular Unleaded, especially as the handbook states that RON95 is the bare minimum to use, reading between the lines would suggest the book implies you should use fuel with a rating higher than RON95.

Searching this topic on Google produces a whole gamut of opinions as to whether it does or doesnt work etc.

One site of particular interest is Thorney Motorsport's fuel tests, originally published in 2006, http://www.thorneymotorsport.co.uk/tuning/Fuel_Test_Results_Update.shtml which whilst interesting doesn't really tell you if the improvedMPG is worth the added cost. Although,after some further delving through google, Idid finda link from Tesco to a .pdf document by Thorney Motorsport which was much more useful for a fuel test done during Q3 of 2009, comparing Tesco RON95 against Tesco Momentum RON 99. Unfortunately this link is now unavailable, but I did manage to save the .pdf file to my machine and will galdly email it to anyone who wants a look, just send me a pm).

In the test they picked 8 cars to represent the different classes of cars driven in the uk at the time, for each class they claim to have picked the best selling car in that class, all were 2008 models bought privately or from second hand dealers this was to ensure that cars were not modified by manufacturers.

One part that I am unlcear on is whether they "tuned" the engine or "remapped" the ECU befor erunning on Momentum, as this was done in some of their previous tests but is not mentioned in this one.
Result Summary<?: prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" />




Total
MilesTotal
Miles

Tesco
RegularTesco
Momentum Total Miles % Increase

Vehicle (95
RON) (99 RON) Difference MPG



Hyundai i10 748 877 129 17.25%

Vauxhall Corsa 1.2
Breeze 948 1106 158 16.67%

Ford Focus 1.6 Zetec 928 1160 23225.00%

BMW 320i M-Sport1195 1419 224 18.74%

Mercedes Benz C180 1323 1615 292 22.07%

Audi TT 1126 1320 194 17.23%

Honda CRV 2.0 981 1214 233 23.75%

Vauxhall Zafira 1.6 1047 1130 83
7.93%



Average 1037 Miles 1230 Miles 193
Miles 18.58%
However this .pdf, and Thorney's tests in general have been called into question on some forums and the advertised results do seem a little difficult to believe. For the time being though, I am prepared to give these tests the benefit of the doubt.

In about a week's time I expect I will need to make my first MPG calculation. I reset the trip counter when I last filled the tank and intend to, deliberately (I am only going to do this once as I do not wish to put undue stress on my engine), run out of fuel so that I can be sure that when I fill up with Super Unleadedthere is little or no Regular Unleaded left in the system.

I will be using Tesco Momentum as used in the Thorney survey, only because I have always filled up at Tesco because they're on my way to/from work and are way cheaper than the BP/Murco filling stations at the end of my Street.

Obviously as I get the results I will post them on here.

What I would like to know from the other owners here, is what sort of fuel economy you are getting.

Specifically I am interested in 1.6SX Station Wagons, but don't be discouraged from posting if you have the 1.8SX wagon or any of the Hatchback Range so please let me know...

1) Which model Lacetti you drive
2) Age and mileage of your car
3) Whetheryou use Regular or Super Unleaded
4) Ifyou have a favoured brand of fuel that you use regularly.
5) MPG currently achieved.

For example: My Car...

1) Lacetti 1.6 SX Station Wagon (Estate)
2) 2009 (09) 41,000 miles
3) Currently using Regular Unleaded, about to change to Premium
4) Tesco
5) Don't know yet buthope it to be at least 26 MPG (www.parkers.co.uk rates fuel consumption at 36MPG)
 

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if you are getting 26mpg that is atrocious! Prior to the epica I had a lacetti1.6sx sw and got a minimum of 30 mpg locally and up to 40mpg if i drove a40 to london on a long run.
Please note that you won't do the catalytic converter any good by running out of fuel, and think too about the safety aspect if you run out in traffic.Edited by: Oldroverboy
 

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Discussion Starter · #3 ·
< ="" ="text/" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">

thanks for the input, reason I said I hoped for 26MPG is that most people who have posted mpg for their cars have posted sub 30MPG figures and so far I have done 220 miles on this fill and the needle is hovering just above 1/4.
I appreciate that running out of fuel on a regular basis will have a dramatic effect on the life of the car, but doing it once shouldn't really damage it, I know its not ideal but its the only way I can make the switch to Super as pure as possible, I will have a can of Fuel in the car so that I cause minimal inconvenience to other road users, plus the roads I drive round on are pretty quiet.
 

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no need to run it compleatly dry.
brim the tank, reset one of the trip's.

whenfuel gets low (light on perm), re-brim the tank. note the litres and miles travelled and calculate.
 

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Discussion Starter · #5 ·
< ="" ="text/" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">

That is what I normally do, and would continue to do were I not changing fuel type. Thing is last time I filled up, with light on permanently I put in about 50 litres, the tank holds 60 litres so there was 10 litres of fuel still in there
not normally a problem as I said, but I'm attempting totest the difference between 95RON and 99RON fuel. if I have 10 litres of 95RON fuel and add 50 litres of 99RON fuel, the resulting tank would actually be around 98.3RON It doesn't sound much, and I probably should notice a difference if there is any to be noted, but I want to be completely sure hence my plan to run dry.

If I had the facility to drain the fuel tank manually I would do that instead, but I don't have that kind of equipment and my tenancy agreement forbids me from storing fuel on the premisis.
 

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Discussion Starter · #7 ·
< ="" ="text/" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">

LOL 1st floor actually but yeah its a flat in a block of 15 not ideal conditions for storing petrol.
 

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Discussion Starter · #8 ·
< ="" ="text/" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">


why do I get all this crappy text aove my posts?


Edited by: KR4G3N
 

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Discussion Starter · #10 ·
Back on topic methinks

Ok so I filled up Thursday last week - My hand was kinda forced by a number of people calling me to tell me the fuel strike may go ahead (which was complete rubbish) but as my fuel light was on I couldn't ignore the possibility that panic buying might prevent me from filling up when I ran out.

Anyway I put in 52 litres of Tesco Momentum 99, this means I had around 8 litres of the regular fuel still in the tank

((8 litres*95RON)+(52 litres*99RON ))/60 = 98.47 RON average for the tank (if it works like that LOL)

its not the pure tank of 99 RON that I wanted but it should hopefully present a noticable difference in fuel economy if there is one to be had.

for the 52 litres of 95RON that I used, I covered 344.5 miles which = 6.625 MPL or 30.117 MPG

The pump price for 95RON/99RON was 140.9/144.9 so filling up with the Momentum cost me and extra £2.08
Cost per mile for the 95RON that I used (had I refilled with 95RON) would be 21.268p/mile so all I need to get out of the 99RON to make it cost effective is an extra 9.5 miles per tank

I will let you know how I get on and if I get 10, 20, 30 or more miles extra out of the 99RON
 

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Today I did 230 motorway miles on 26.2 litres of regular unleaded in my '58 reg 1.8 auto station wagon with 8,500 miles on the clock which works out at 40+ mpg. My normal running is a 50 / 50 mixture of town and motorway driving which usually works out at 32 - 34 mpg.
 

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When i had the 1.6 sx estate i only ever got the same mileages as that, so well done, i anticipate lots of thought in your driving habits. very very good.
 

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Lacettis are not the most frugal of cars, but with some limitations ' keeping revs to a minimum' i.e cutting down on excessive hard acceleration they can still be good to drive and reasonably economical. I have found 70 mph on minimal throttle is a lot more economical than 80+ and does not make that much difference to overall journey time.
 

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Discussion Starter · #14 ·
< ="" ="text/" ="/B1D671CF-E532-4481-99AA-19F420D90332etdefender/huidhui.js?0=0&0=0&0=0">

Ok quick update for you on my tests, just filled up my tank today, light wasn't on but I have a motorway trip tomorrow so had to fill up today to get most accurate results.
Quick recap My last fill was done having used a full tank of Tesco 95 RON where I used 52 litres in 344.5 miles (6.625 mpl or 30.117858705 mpg). Based on this a full 60l tank should travel 397.5 miles

When I filled up I switched to the Tescom Momentum 99 RON and when I filled up today, I put in 48 litres for a distance travelled of 328.6 miles. (6.845833333333333 mpl or 31.1217873285 mpg) Based on this, a full 60l tank should travel 410.75 miles.

A difference of 13.25 miles per tank

so is it worth it? well the price difference between 95 & 99 RON varies but the 99 RON is normally around 4-7p/l more expensive.

I have a 60l tank so that is a price difference of between £2.40-£4.20 per tank

Currently my local Tesco is selling the 95 RON at 135.9p/l with 99 RON at 142.9p/l total costs for a 60l fill being £81.54 for the 95 RON and £85.74 for 99 RON

Based on the above information, the difference is barely noticable and only worth the money if the price difference for the momentum is less than £2.75 (4.5p/l) anything over that is unlikely to provide a financially beneficial difference.

But it was an interesting experiment, worth investigating :p
 

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On my previous car which was a Rover 45 1.8 auto I experimented with super unleaded and found with the price difference it wasn't really any better but used to put some in now and again as it ran slightly smoother. I think the most important thing is how much throttle you are using. If I drive at 65 - 70 on light throttle on the motorway say 2.500 rpm it is much more economical than doing 75+ at 3000+ rpm common sense really. I sometimes think that 'going with the flow' of other cars can make you go that little bit faster than you need to and use more petrol, it depends what mood I am in.
 
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