Sorry fellas it's MPG again.

[John Ratsey]

I do agree that 29 mpg is abymal. However I am driving the same as last year and always try to keep the green light on. I'm a senior so no harsh breaking. All cold starts and urban driving.
My previous Mk3 manual gave better results.
Maybe I should drive it a bit more positively rather than trying for economy.

Perhaps the basic question is therefore why the CVT Mk 3 is giving significantly worse MPG than the manual Mk 3 you drove previously for the same route and driving conditions?
Does your CVT Mk 3 give similar engine speed behaviour to you driving the manual version? I drove the Mk 3 CVT for a year and didn't like the way it piled on the revs every time I applied more than very light pressure on the accelerator pedal.

I agree that cold engines and short trips give abysmal fuel economy. If it were easy to block off most of the radiator and reduce the flow of cold air into the engine compartment during the winter months then I would. My current work-around is that I normally leave the heater fan off for the first couple of miles to help the coolant warm up.

[Jocko]

I never switch to "Warm" until the blue light goes out.

[jazzaro]

The GK3 blue light goes out ad 43°C, but the climate control turns on the fan some seconds before, I suppose at about  40°C and the air is quite hot.

[culzean]

Quickest way to warm and engine is driving, not ticking over on the driveway.  You shouldn't over-rev a cold engine but just pottering at low revs means it take longer to warm up - I once read that pretty much every engine does 25mpg when cold ...  I used to block off radiator grill on cars, but they used to have big fans driven by the engine that were constantly rotating and sucking cold air through radiator matrix and blowing it over the engine, modern cars with electric fans you will never see the fan switch on in winter ( unless you are using aircon or climate control ),  and maybe not even in summer unless in traffic and really hot weather ( unless using aircon )..

[sparky Paul]

I used to block off radiator grill on cars, but they used to have big fans driven by the engine that were constantly rotating and sucking cold air through radiator matrix and blowing it over the engine, modern cars with electric fans you will never see the fan switch on in winter ( unless you are using aircon or climate control ),  and maybe not even in summer unless in traffic and really hot weather ( unless using aircon )..

In the pursuit of efficiency, some modern cars are now being fitted with electric shutters on the front grille to stop the entry of cold air such as Ford's 'Active Grille Shutter'. They are primarily to aid aerodynamics, but are also to help shorten warm up times.

Can you remember carburettor cars with a winter position for the air filter intake, pulling air from the back of the engine?

[madasafish]

Quickest way to warm and engine is driving, not ticking over on the driveway.  You shouldn't over-rev a cold engine but just pottering at low revs means it take longer to warm up - I once read that pretty much every engine does 25mpg when cold ...  I used to block off radiator grill on cars, but they used to have big fans driven by the engine that were constantly rotating and sucking cold air through radiator matrix and blowing it over the engine, modern cars with electric fans you will never see the fan switch on in winter ( unless you are using aircon or climate control ),  and maybe not even in summer unless in traffic and really hot weather ( unless using aircon )..

If I turn left out of our drive , I then have a 1 mile drive on a twisty slow road up a steep hill (+100meters high) . If I had zeroed the trip before starting from cold , my MPG then reads 12 to 14mpg....

[Downsizer]

Can you remember carburettor cars with a winter position for the air filter intake, pulling air from the back of the engine?

20 mpg was good in those days.   Also, cars had no heaters, so travel in winter involved bulky clothes, gloves, and rugs for passengers!

[Jocko]

The ScanGauge data is interesting, I would never have thought it would be more economical to drive up a hill in 5th with my foot flat to the floor, does the engine management system then limit the amount of fuel supplied to the injectors ?

Climbing that particular hill this morning and I was thinking about your question. With a modern engine the amount of fuel burnt depends on the amount of air being drawn into the engine. The amount of air drawn in depends on the throttle position, but also on the rpm. Higher revs draws in more air for a given throttle position. My full throttle at low revs uses draws in less air than 4th or 3rd gear at higher revs and less throttle, therefore uses less fuel.
Unless someone knows otherwise.

[Jocko]

Also, cars had no heaters, so travel in winter involved bulky clothes, gloves, and rugs for passengers!

I have had cars from the early 50s on, and they all had heaters. Mind you, they were an optional extra on a new Ford in 1956.

[sparky Paul]

Can you remember carburettor cars with a winter position for the air filter intake, pulling air from the back of the engine?

20 mpg was good in those days.   Also, cars had no heaters, so travel in winter involved bulky clothes, gloves, and rugs for passengers!

Not going that far back, I'm not that old!

Other half had a 1985 Renault Super 5 with the movable elephant's trunk attached to the air filter, you could attach it to a box around the exhaust manifold for winter.

[culzean]

I used to block off radiator grill on cars, but they used to have big fans driven by the engine that were constantly rotating and sucking cold air through radiator matrix and blowing it over the engine, modern cars with electric fans you will never see the fan switch on in winter ( unless you are using aircon or climate control ),  and maybe not even in summer unless in traffic and really hot weather ( unless using aircon )..

In the pursuit of efficiency, some modern cars are now being fitted with electric shutters on the front grille to stop the entry of cold air such as Ford's 'Active Grille Shutter'. They are primarily to aid aerodynamics, but are also to help shorten warm up times.

Can you remember carburettor cars with a winter position for the air filter intake, pulling air from the back of the engine?

Yes,  cars had a lever or a hose that you moved to pull air from over the exhaust manifold.   Also had engine coolant flowing around carburetor to warm it up or prevent it freezing when the air was rushing through vapourising fuel - I can remember during the harsh winter of 1982/3 when my Vauxhall would not start despite having a good spark and fuel, had a lightbulb moment and used her-indoors hairdryer on the carb, and it started ok - that was the year the daytime temperature went down below -20degC and stayed there for weeks, even colder at night.. had to do the hairdryer trick for weeks before starting car to get to work.   

[Basil]

The ScanGauge data is interesting, I would never have thought it would be more economical to drive up a hill in 5th with my foot flat to the floor, does the engine management system then limit the amount of fuel supplied to the injectors ?

Climbing that particular hill this morning and I was thinking about your question. With a modern engine the amount of fuel burnt depends on the amount of air being drawn into the engine. The amount of air drawn in depends on the throttle position, but also on the rpm. Higher revs draws in more air for a given throttle position. My full throttle at low revs uses draws in less air than 4th or 3rd gear at higher revs and less throttle, therefore uses less fuel.
Unless someone knows otherwise.

That makes sense, I didn't really think of engine speed being a factor.

What sort of revs do you get down to ?

[Jocko]

What sort of revs do you get down to ?

I'm not sure. I'll check it out the next time I am on that hill.

[culzean]

What sort of revs do you get down to ?

I'm not sure. I'll check it out the next time I am on that hill.

Bear in mind the i-DSi engine is much happier and tractable at low revs than the later V-tec engines....

[Basil]

What sort of revs do you get down to ?

I'm not sure. I'll check it out the next time I am on that hill.

Bear in mind the i-DSi engine is much happier and tractable at low revs than the later V-tec engines....

Fair point, I've not driven that version but I might change my technique and see how it feels.