28MPG from a 1.25 fiesta...
Discussion
Hi guys,
Been monitoring my car's MPG lately, from brim to empty (40l/8.8gall tank). Last few fills netted me about 36mpg, mix between town driving, motorways (cruising between 80 and a ton) and some country hooning (maybe 30-40 miles worth on a tank). Last tank got 28 MPG
. And that wasn't a "rough" brim to empty, that was a click then click again then click again type fill, and then I ran it so far into the fuel light that it coughed and cut out going up hill; I then got 39.3 litres before it clicked off, so less than a litre left in the tank. It managed to do 250 miles on 40 litres worth of petrol, an absolutely shocking figure. This was with a fair bit of town driving, with some short starts (maybe 6-7 miles each time), about 160 miles on the motorway (again cruising between 80 and a ton) and about 40 miles on empty country lanes.
Now I do have quite a heavy right foot but 28MPG? I didn't even think it was capable of going that low. What sort of things should I check up on? Oil levels seem fine, engine is running fine, haven't checked brakes/bearings yet but it will gladly cruise up to an indicated 110 which is the book top speed so I doubt it's a sticking caliper, or else it wouldn't be able to match that? Tyre pressures were topped up before that fill to 36/32PSI F/R. I've heard puma owners saying their 1.7s never dip below 30 no matter what, so 28mpg on a 1.25 is pretty shocking.
Any advice on what action to take would be great, and anyone else with experience of 1.25 mk4/5 fiestas please share your usual MPG/useage.
Been monitoring my car's MPG lately, from brim to empty (40l/8.8gall tank). Last few fills netted me about 36mpg, mix between town driving, motorways (cruising between 80 and a ton) and some country hooning (maybe 30-40 miles worth on a tank). Last tank got 28 MPG
. And that wasn't a "rough" brim to empty, that was a click then click again then click again type fill, and then I ran it so far into the fuel light that it coughed and cut out going up hill; I then got 39.3 litres before it clicked off, so less than a litre left in the tank. It managed to do 250 miles on 40 litres worth of petrol, an absolutely shocking figure. This was with a fair bit of town driving, with some short starts (maybe 6-7 miles each time), about 160 miles on the motorway (again cruising between 80 and a ton) and about 40 miles on empty country lanes. Now I do have quite a heavy right foot but 28MPG? I didn't even think it was capable of going that low. What sort of things should I check up on? Oil levels seem fine, engine is running fine, haven't checked brakes/bearings yet but it will gladly cruise up to an indicated 110 which is the book top speed so I doubt it's a sticking caliper, or else it wouldn't be able to match that? Tyre pressures were topped up before that fill to 36/32PSI F/R. I've heard puma owners saying their 1.7s never dip below 30 no matter what, so 28mpg on a 1.25 is pretty shocking.
Any advice on what action to take would be great, and anyone else with experience of 1.25 mk4/5 fiestas please share your usual MPG/useage.
Edited by Gooly on Tuesday 13th November 02:50
Reduce your motorway speeds down to 70 or below and I bet it will increase dramatically. At the speeds you're doing, you're probably working the little engine quite hard and at high-revs with the short ratios.
Also when town driving try to avoid using the brakes as much as possible as they waste fuel turning the kinetic energy into heat. Instead plan as far forward as possible.
I do nothing but town driving and manage to get 32mpg from a 1.8 petrol, 1.5 ton 7 seat Grand Picasso.
Also when town driving try to avoid using the brakes as much as possible as they waste fuel turning the kinetic energy into heat. Instead plan as far forward as possible.
I do nothing but town driving and manage to get 32mpg from a 1.8 petrol, 1.5 ton 7 seat Grand Picasso.
TheTurbonator said:
Reduce your motorway speeds down to 70 or below and I bet it will increase dramatically.
THISA 1.25 fiesta isn't designed to cruise at those speeds, you must be revving the tits off it?
Plus its actually quite dangerous in something like that as the brakes, tyres and suspension aren't designed for that sort of driving.A - Should the driver need to avoid a collision or brake suddenly)
Edited by Jonty355 on Tuesday 13th November 17:46
Whilst I might disagree that the brakes and suspension wouldn't take it, I would definitely say that you are really pushing the performance. I'm sure they sold Fiesta 1.25s in Germany and endurance tested them at well over 100mph. There is a difference though between something working, and something working well.
When you open the throttle more than 75% (it varies from one model to the next) the engine management goes into "WOT" mode (=Wide Open Throttle). This stops taking the signal from the exhaust oxygen sensor, and enriches the mixture, instead of trying to generate a perfect stoichiometric ratio. Basically, it is a sort of emergency power demand, where efficiency and emissions go out of the window, in return for some extra performance. I'm pretty sure that at the sort of speeds you were talking about, you are well into this engine management map.
If you ease off and go with the normal traffic flow, rather than hooning it down the outside lane, then I reckon your consumption should head back towards 40mpg.
If you are still getting poor consumption at lower speeds (and less throttle) then consider getting the ECU codes read, as there might be a faulty sensor causing over-enrichment.
When you open the throttle more than 75% (it varies from one model to the next) the engine management goes into "WOT" mode (=Wide Open Throttle). This stops taking the signal from the exhaust oxygen sensor, and enriches the mixture, instead of trying to generate a perfect stoichiometric ratio. Basically, it is a sort of emergency power demand, where efficiency and emissions go out of the window, in return for some extra performance. I'm pretty sure that at the sort of speeds you were talking about, you are well into this engine management map.
If you ease off and go with the normal traffic flow, rather than hooning it down the outside lane, then I reckon your consumption should head back towards 40mpg.
If you are still getting poor consumption at lower speeds (and less throttle) then consider getting the ECU codes read, as there might be a faulty sensor causing over-enrichment.
28 mpg sounds pretty good for town driving + high speed cruising. Shirley you're well above 4k revs on the motorway.
The main problem with fuel consumption at motorway speeds of above 60 odds is the fuel required to accelerate back to speed as I find you often get stuck behind a 60 mpher overtaking a 58 mpher and such things.
Advice: if your time is worth the fuel costs, keep doing as you are just now.
If you'd rather take a few minutes longer per journey, leave a bit earlier and cruise at a more leisurely pace should see you saving fuel.
I don't find it helpful to think of "braking uses up fuel". I prefer to think "do I need to accelerate here?" eg if in a queue of traffic in town, moving up to red lights, many seem to enjoy going as fast as they can then braking again before the car in front. This is fuel intensive, too. Slowing down does not use fuel, it's the needless acceleration beforehand that does.
You may also prefer to think of using the accelerator as an investment in fuel economy, i.e. only accelerate if it's actually going to save you fuel. Up to a green light to get through it may be a worthwhile spurt, but from the back of one queue to the next certainly isn't.
The main problem with fuel consumption at motorway speeds of above 60 odds is the fuel required to accelerate back to speed as I find you often get stuck behind a 60 mpher overtaking a 58 mpher and such things.
Advice: if your time is worth the fuel costs, keep doing as you are just now.
If you'd rather take a few minutes longer per journey, leave a bit earlier and cruise at a more leisurely pace should see you saving fuel.
I don't find it helpful to think of "braking uses up fuel". I prefer to think "do I need to accelerate here?" eg if in a queue of traffic in town, moving up to red lights, many seem to enjoy going as fast as they can then braking again before the car in front. This is fuel intensive, too. Slowing down does not use fuel, it's the needless acceleration beforehand that does.
You may also prefer to think of using the accelerator as an investment in fuel economy, i.e. only accelerate if it's actually going to save you fuel. Up to a green light to get through it may be a worthwhile spurt, but from the back of one queue to the next certainly isn't.
There are exceptions of course but in general 1 litre'ish engines at 90 mph + are significantly less efficient than a 2 litre at the same speed. One of the very overlooked points about small car / engine motoring, and rarely given up in MPG statistics by manufacturers or the government.
As an aside I wonder if there should be a requirement for cars sold (lead by customer demand) to have what used to be called and "overdrive gear" - the most efficient gearing for that car with 2 adults and 1/2 a tank of petrol to cruise at 120 KPH say, with the lowest reves required to maintain that on the straight and leve. If you want to speed up then you change down. SO the highest gear you have is not a perfromance gear in any way shape or form, but simply and economy gear for cruising ?
As an aside I wonder if there should be a requirement for cars sold (lead by customer demand) to have what used to be called and "overdrive gear" - the most efficient gearing for that car with 2 adults and 1/2 a tank of petrol to cruise at 120 KPH say, with the lowest reves required to maintain that on the straight and leve. If you want to speed up then you change down. SO the highest gear you have is not a perfromance gear in any way shape or form, but simply and economy gear for cruising ?
Gooly said:
Hi guys,
This was with a fair bit of town driving, with some short starts (maybe 6-7 miles each time), about 160 miles on the motorway (again cruising between 80 and a ton) and about 40 miles on empty country lanes.
As mentioned this is the issue, such a small engine will not be very efficient at >80mph. How many revs is it pulling at that speed? Drop to 65-70 and I suspect the mpg improvement will be dramatic.This was with a fair bit of town driving, with some short starts (maybe 6-7 miles each time), about 160 miles on the motorway (again cruising between 80 and a ton) and about 40 miles on empty country lanes.
Edited by Gooly on Tuesday 13th November 02:50
Zad said:
Whilst I might disagree that the brakes and suspension wouldn't take it, I would definitely say that you are really pushing the performance.
Not in any way saying they wouldn't take it, I'm sure you could drive at a ton+ all day long. However, should the fiesta driver have to brake or swerve, its probably not going to end well as the car is not designed to corner or brake at those speeds
I drive my little commuting Ka like a saint. On weekdays it'll do a couple of miles of town traffic, 15 miles of B-roads and 15 miles of A-roads each day. From 36 litres I'll easily manage 360 miles (around 45mpg), which isn't so bad. If you're persistently running WOT between 80-100mph, are you genuinely surprised you're getting 28mpg?
I think you're heading towards engine death. Many moons ago I had a 1.1 Fiesta, and drove just like you... Like I needed to be everywhere ten minutes ago. Motorway cruising circa 90mph etc with it screaming its tits off!
When I bought it it ran like a dream, after about 6 months the mpg dropped, and about a month later it dropped a piston ring whilst in lane 3 of the M4 at rush hour. Engine lunched. Weighed it in.
You have been warned!
When I bought it it ran like a dream, after about 6 months the mpg dropped, and about a month later it dropped a piston ring whilst in lane 3 of the M4 at rush hour. Engine lunched. Weighed it in.
You have been warned!
Porkie said:
LOOK AT THE REV COUNTER FOR GODS SAKE!
Maybe it doesn't have one?! I agree with you though, little Yamaha unit isn't it? My buddy had one in a Fiesta also and it went really well for it's size, power delivery was very smooth and it loved to rev.
The OP is quite simply driving too fast.
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