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New Car Poor MPG

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  • New Car Poor MPG

    First step, check tyre pressures. Set for eco setting's.

    Many people think these engines take time to bed in and achieve anywhere within a country mile of the advertised mpg #'s

  • #2
    Fairly new to this myself, only had mine for about a month.

    I do about 35k a year commuing so eco is very important to me too.

    I run about 36psi in mine and currently get about 50mpg. I plan to get this higher, but think this is partially me getting used to the car.

    The eco on mine is the same as yours, although I run 36 as I imagine 41 will be a bit of a hard ride.

    I use 36, due to an old rule of ((2x rim size)+2). Seems ok at the moment.

    The comfort settings are for town driving and low mileage to be honest, dependant on the wheel size try the calculation above.


    • #3
      Hi and welcome to the forum. I think, along with myself, there are a multitude of owners who would chew your arm off for 67mpg!!!??That said, I realise you have a different vehicle to most of us, so you need info from someone who has that type of car. Could well be to do with tyre pressure for at least part of the problem.


      • #4
        45 is low for motorway driving. Think a few have found setting the CC at 67 to be the optimum speed for mpg! I'm guessing you have not done a lot if miles since you've only had it a week! It should loosen off a little once over 2-3k. If it doesn't improve with motorway driving I'd get it back in. You'd expect approx 10-15% under the stated mpg but that a good 35 ish under!

        And yes, Andy is right, 28 mpg average from my 160 before I got shot of it.


        • #5
          I would agree with what you should expect. Try resetting the mpg once you are on motorway and see if it goes up. Also run it a while with instant mpg to see what you are getting!


          • #6
            I am currently using the instant mpg readout to learn my car's optimum.

            Amazing how much the smallest adjustments make quite a difference.

            Example, moving through b road traffic tickling throttle to keep at 30mph in 4th, requires much heavier throttle use then the same speed in 3rd.

            Equally making the engine labour in any way uses more fuel, try not to use 6th until at least 60mph.


            • #7
              It's the long gearing of the ecoflex that will be causing that! Non-Ecoflex you should be able to bump it into 6th at around 45-50 without any labouring!


              • #8
                Mines not an ecoflex, just by what the mpg readout is saying on instantaneous readout.

                If the insignia is anything like my vec c, 1500-1800 rpm seems to be the bottom of the range for eco unless going downhill with the wind behind you.

                Happy to be proven wrong, only had the car a month...


                • #9
                  The engine certainly takes a while to bed in so you won't see great figures for the first few thousand I'd imagine


                  • #10
                    andyellis111, on 02 January 2014 - 04:48 PM, said:
                    If I used that, mine would be running on 40psi for front and rear?!

                    Won't that make my spine crumble?

                    Indeed it probably would, which is why I also stated i think this maybe a little bit of a harsh ride.

                    It's an old rule, that we used for alloy wheel fitment in an old job of mine. Bear in mind that 17" alloys were classed as massive at that time and 18" wheels wetre almost mythical.

                    I just use it as a good starting point to be moved up or down based on comfort/eco desires.


                    • #11
                      andyellis111, on 02 January 2014 - 05:18 PM, said:
                      Agreed. I currently have mine @ 32 and 29 for front and rears respectively, on my 19s but I imagine I could get much more mpg if I increased it a little....just don't like the hard ride causes more rattles!

                      Absolutely, 41psi recommended on mine for eco, which is great but don't think my spine would thank me...


                      • #12
                        Also bear in mind, it isn't about just the cruising speed, it's about how you get there, using brakes less, using engine breaking and gears to slow down etc


                        • #13
                          bear in mind that you will never get anywhere near the stated mpg when you have bigger alloys / tyres as these also affect mpg.
                          Insignia Elite Nav 2ltr SIDI Turbo 250PS, Pearlescent Emerald Green, VX-Line Interior, VX-Line Exterior Styling Kit, Premium Brandy Nappa Sports Leather, 20" Elite Multi Spoke Alloy Wheels, 8" Digital Drivers Display, Bose Premium Audio System, Front Camera Pack, Rear View Camera, Adaptive Cruise Control, Advanced Park Assist, Rear Privacy Glass, Keyless Entry & Start, Tyre Pressure Monitoring System, Factory Fitted Towbar


                          • #14
                            Hi "InsigLTD"

                            Welcome to the forum.

                            In my opinion, the EcoFlex models, with their taller gearing are probably more efficient at between 75 and 80mph. Ideally, the engine should be turning at about 1700 - 1800 rpm.

                            It may seem a bit perverse, but if the cruise is set to 67, the car might actually be more economical if left in 5th gear.

                            The point you made about about swapping the wheels affecting the trip computer would depend on the sizes involved.

                            245/45x18 and 245/40x19 tyres have identical rolling radii, so the trip computer and speedometer would not need to be reprogrammed, if??these were the sizes that were swapped.

                            Also, bear in mind that the prevailing weather conditions make a big difference to the fuel efficiency of a car.

                            I don't know what the conditions were like when you put on the first 850 miles.

                            But, there has certainly been some horrendous weather since christmas eve.

                            Low temperatures, wet roads and high winds can all conspire to hammer a car's fuel efficiency.

                            The published eco figures are measured on a rolling road for consistency, so there is no wind resistance to account for.

                            When tested, the car must have done a minimum of 1800 miles (3000km). The ambient temperature during the test must be between 20oC and 30oC

                            To achieve the most favourable test result, the manufacturer will set the tyre pressures at the maximum recommended pressures.

                            All electrical accessories will be turned off, as will the aircon. And the battery will be fully charged before the test is started, to ensure minimal charging load on the alternator.

                            And as quoted in the small print, test figures are for comparison purposes only. They do not guarantee actual performance in normal service, and individual cars may vary.

                            John LE, on 06 January 2014 - 11:17 PM, said:
                            I'm running the same tyre pressures as you and have the 19" atomic wheels too. Try running the car at 70 and wait until there is about 1500 miles on the clock before you start worrying

                            I agree with John's comment. Although, I would wait until I had done at least 4000 miles before I started to worry.
                            Elite ST 2.0i Auto. Power Red With All The Toys


                            • #15
                              Dpf deletes are an mot fail. Simple as that