my car is bad on fuel!!!!!

[guest780]

i have a 2004 jazz se.
it has now 95000 on the clock.   its only given me 32mpg.
does any one know what i could do to bring the mpg up.
i drive in high gears and  at a regular speeds.

[culzean]

Are your miles all short stop-start journeys around town? Is the car serviced regularly and have the spark plugs been changed recently? have the brakes checked to make sure they are not dragging (feel the wheels and wheel studs as soon as you stop the car after a journey, if one is a lot hotter than the others suspect that the brakes on that wheel are binding). Try adding some fuel injector cleaner to your petrol for a couple of tanks.

It's acceleration that uses up the fuel, try to change up as early as possible - the Jazz is quite happy to be in 3rd gear by 30mph unless you are going up a hill. 

[JazzyB]

'the Jazz is quite happy to be in 3rd gear by 30mph  '

Im normally in 4th gear at 30 mph

[guest780]

the car has been serviced all at the right times and has everything that needed changing at service changed.
i put £20 fuel and managed to get 150 miles. surely this cant be right for a small car like this.
i drove 85 of those miles on a one way journey on the motorway 65 miles in town. i this right?

[RichardA]

Do you keep the tank topped up? Try waiting until the low fuel light comes on and fill-up the tank right to the top. I get better mpg on full tanks then I do if I keep it topped up weekly.

[guest516]

My sport auto over the last year & 10468 miles averaged 44mpg - best 1000 miles last March at 47.6 - December/January distinct drop some weeks of cold weather starts & local miles stop/start - feel a service will restore everything !
New Jazz ES i-shift on drive now so unable to say if service worked
I always fill-up & keep a constant record

[guest780]

i was thinking of using the injector cleaner petrol treatment.
maybe this will help. has any 1 used this and seen  positive affect?
also could it be the type of unleaded i use. lately i have been using the cheaper unleaded at tesco. should i use the super unleaded instead.

[RichardA]

Try a couple of tankfuls of super unleaded from one of the major brands, it may 'clean' the system out. I've seen an improvement in using super unleaded, *but* the figures remained improved if I returned to normal unleaded.

I doubt the injector cleaner would work though.

Your Jazz is quite high mileage, although I would still expect better than the low 30's.

[JazzyB]

Normal unleaded is fine, using the super stuff gives no benefit either economy or performance.
I use a petrol treatment once a year just as a precaution

[JazzyB]

Sick Motor?
Lost power, high fuel consumption, rough acceleration, exhaust smoke or just won't start.
Any of these sound familiar?
You may have a fuel system problem that could be fixed with the DIY application of D-TOX,
a powerful combustion chamber and fuel system cleaner.

A common fuel system problem affecting modern cars is the build up of combustion chamber deposits. Harmful deposits gradually accumulate and clog up fuel systems and the injectors, seriously affecting your engine's performance. Carbon deposits can also accumulate in the combustion chamber, piston and upper cylinder area, and unless removed with D-TOX they may eventually flake off, settle on the valve seat so the engine loses compression and then will not start. D-TOX breaks down these deposits to allow them to be exhausted without harm whilst at the same time acting as a powerful cleaner throughout the complete fuel system. D-TOX is formulated for use in all petrol / gasoline engines including those with turbo and super chargers, carburettors, multi valves, direct and indirect injection systems, and its catalytic converter friendly. We recommend using D-TOX once your engine is a year old and then again every year or 10,000 miles/16,000km or when reduced performance is noticed.

The above is the Comma petrol D-tox which I use on a yearly basis
 

[culzean]

Of course injector cleaners work - I use them about twice a year.  Think of then like kettle de-scaler, no-one says that they don't work because the evidence is clear to see.  Petrol from reputable garages (and I exclude supermarket petrol here because they cut costs by reducing the additives) has stuff in it to keep the injectors clean, but the less miles you do the more the injectors tend to clog up.

People think that the petrol that they put in their tank is really clean, but it isn't - its made from that yucky thick tarry stuff that is pumped from underground, and it leaves gunky deposits in your fuel system, especially the fine injector nozzles.  Injector cleaners mainly have kerosene or similar as their main ingredient to dissolve this gunk.  Anyone who has ever used carburettor cleaner knows how quickly it could turn a carb gunged up with sticky brown laquer into a sqeaky clean shining piece of precision engineering.

[RichardA]

Normal unleaded is fine, using the super stuff gives no benefit either economy or performance.
I use a petrol treatment once a year just as a precaution

What I mean is it might clean the system out which in turn could improve mpg. Does it actully also have cleaners in the fuel like some say it does? Directly, no gain will be made in performance or economy as the engine won't take advantage of the higher octane rating.

The injector cleaner I got confused with those performance enhancers you stick in your tank.

[culzean]

Since manufacturers started sticking mpg displays in cars people have really become anoraks about their fuel consumption.  Before the displays became common only a few people really checked their mileage against the amount of fuel they put in their tank and no-one challenged the car makers claims.  The facts are that the following things all have a big effect on fuel consumption - start-stop driving and rapid acceleration, speeding**,  not changing to a higher gear soon enough, short journeys, cold weather, incorrect pressure in tyres. 

** Remember that air resistance is not linear - it increases rapidly as the speed rises. Even on modern streamlined cars the wind resistance really starts to increase your fuel consumption above 30mph  - you will use about a third less fuel by travelling at 45mph instead of 70mph.

[guest238]

Try working out the mpg and not going by the trip computer.

Is this problem something which has only recently occured?

[guest238]

Forget the injector cleaner, just try the Italian Tuneup and some decent quality fuel (super unleaded or branded unleaded).