MPG... Good urban, poor extra urban... Explain please...
Discussion
I own a 1999 Honda CRV. It's a 2.0l 16v petrol. Puts out around 150hp, not that it's relevant to the question.
Without fail, I get 350 miles to a full tank (55l) of petrol. Doesn't matter if I rag it or pootle about like a saint. Always 350 miles, unless I take it on the motorway.
My usual commute is around 5 miles of stop start traffic. Lots of lights and crawling around a mile at the end of it. I average around 28-29mpg doing a full tank of this commute.
Over the last tank, I did all motorway, crusing at 70-75, if not slower due to roadworks etc. Never pushing it hard, just cruising. I had to fill up at 300 miles, giving a pretty poor 24mpg.
It defies logic really and has me stumped. Anyone have an explanation or is it just a "4x4" thing of being piss poor at motorway crusing?
Without fail, I get 350 miles to a full tank (55l) of petrol. Doesn't matter if I rag it or pootle about like a saint. Always 350 miles, unless I take it on the motorway.
My usual commute is around 5 miles of stop start traffic. Lots of lights and crawling around a mile at the end of it. I average around 28-29mpg doing a full tank of this commute.
Over the last tank, I did all motorway, crusing at 70-75, if not slower due to roadworks etc. Never pushing it hard, just cruising. I had to fill up at 300 miles, giving a pretty poor 24mpg.
It defies logic really and has me stumped. Anyone have an explanation or is it just a "4x4" thing of being piss poor at motorway crusing?
The faster you travel the more resistance you create.
A 4x4 has transmission losses, lots air resistance thanks to the aerodynamics of a shed, rolling resistance from big tyres and that Ginsters pasty you picked up to contend with.
Lay off the pasties or buy a prius instead of killing the planet
A 4x4 has transmission losses, lots air resistance thanks to the aerodynamics of a shed, rolling resistance from big tyres and that Ginsters pasty you picked up to contend with.
Lay off the pasties or buy a prius instead of killing the planet
Wife uses a Toyota Auris 1.3 for local urban and suburban stuff. Due to stop start tech etc and the way the engine and gearing are set up, the ave mpg actually drops if I use it for a mway run at lane 3 speeds. At this pace my old 530i would get into the groove and the mpg would climb. The little buzz box is straining its arse off, often requiring 4th gear and 5000rpm in order to have any responsiveness.
So it's just a "4x4" being generally crap at motorway crusing then...
Gearing seems fine. Doubt anyone would mess with it as it's hardly a hardcore 4x4. Just a softroader. Sits at around 3200rpm at 70mph which seems normal to me. I always find Hondas to have lowish ratios anyway. The CRV has plenty of response at 70mph.
A slightly longer 5th with a 70 cruise at 2500rpm would have done wonders and not really lost much pulling power.
Gearing seems fine. Doubt anyone would mess with it as it's hardly a hardcore 4x4. Just a softroader. Sits at around 3200rpm at 70mph which seems normal to me. I always find Hondas to have lowish ratios anyway. The CRV has plenty of response at 70mph.
A slightly longer 5th with a 70 cruise at 2500rpm would have done wonders and not really lost much pulling power.
We experience similar with our 1.3 Mazda 2.
It's ok around town, but frankly awful on the open road getting 30mpg on a good day. Cars were returning better economy than that in the 80's ,and it makes the 30mpg out to the 328i or 26mpg out of the Impreza seem like value for money.
Try hypermiling techniques ,check tyre geometry and pressure, but I expect that it's a feature of a 4x4 with a diddy engine. Certainly my Mother In Laws Mitsubishi Pinin returns similarly bad Mpg.
It's ok around town, but frankly awful on the open road getting 30mpg on a good day. Cars were returning better economy than that in the 80's ,and it makes the 30mpg out to the 328i or 26mpg out of the Impreza seem like value for money.
Try hypermiling techniques ,check tyre geometry and pressure, but I expect that it's a feature of a 4x4 with a diddy engine. Certainly my Mother In Laws Mitsubishi Pinin returns similarly bad Mpg.
Deluded said:
I own a 1999 Honda CRV. It's a 2.0l 16v petrol. Puts out around 150hp, not that it's relevant to the question.
Without fail, I get 350 miles to a full tank (55l) of petrol. Doesn't matter if I rag it or pootle about like a saint. Always 350 miles, unless I take it on the motorway.
My usual commute is around 5 miles of stop start traffic. Lots of lights and crawling around a mile at the end of it. I average around 28-29mpg doing a full tank of this commute.
Over the last tank, I did all motorway, crusing at 70-75, if not slower due to roadworks etc. Never pushing it hard, just cruising. I had to fill up at 300 miles, giving a pretty poor 24mpg.
It defies logic really and has me stumped. Anyone have an explanation or is it just a "4x4" thing of being piss poor at motorway crusing?
mpg is generally affected more by the amount of throttle you use rather than actual rpms, e.g. a light throttle at high rpms will use less fuel and a wide open throttle at low engine speeds.Without fail, I get 350 miles to a full tank (55l) of petrol. Doesn't matter if I rag it or pootle about like a saint. Always 350 miles, unless I take it on the motorway.
My usual commute is around 5 miles of stop start traffic. Lots of lights and crawling around a mile at the end of it. I average around 28-29mpg doing a full tank of this commute.
Over the last tank, I did all motorway, crusing at 70-75, if not slower due to roadworks etc. Never pushing it hard, just cruising. I had to fill up at 300 miles, giving a pretty poor 24mpg.
It defies logic really and has me stumped. Anyone have an explanation or is it just a "4x4" thing of being piss poor at motorway crusing?
With regards to your HRV, have you owned it long and has it always done this?
Arguably stop start traffic using a light throttle can actually be fairly economical and queuing for a mile isn't really that far, remember at tickover the engine is using a very small amount of fuel.
Also a CRV is somewhat of a brick aerodynamically speaking, it's not the lightest and despite being 2wd most of the time, still pays a penalty with additional drivetrain loses and friction due to the gubbins that makes up the rear drivetrain (shafts, clutches, etc).
Taking all this into account and that something like a CRV isn't going to have a tall final drive ratio, I bet running at 75mph on the motorway is not only quite high rpms (over 3000, maybe pushing on for 4000rpm). Even more so if this is GPS 75mph and not speedo 75mph. But the weight and aero properties of the car will require quite an open throttle, again even more so if there where lots of hills.
I'd be willing to be if you repeated the motorway journey at 60-65mph that you'd see a massive improvement in mpg.
In something as lightweight as my smart Roadster running at 60-65mph on the motorway will typically yield ~58-62mpg, however running at the speeds you describe will see it drop to nearer 48mpg.
300bhp/ton said:
mpg is generally affected more by the amount of throttle you use rather than actual rpms, e.g. a light throttle at high rpms will use less fuel and a wide open throttle at low engine speeds.
Actually, light throttle at high RPMs is almost invariably significantly worse for fuel consumption than higher throttle openings at lower RPMs.More revs means more friction and Dethrottling means less pumping loss, and as long as you're not hoofing it enough to get into overfuelling to keep things cool (probably a third to half throttle on turbos, three quarters on N/A) then you're more likely to be getting closer to the engine's peak efficiency.
Yes if you're at low enough revs and large enough throttle openings to get into poor gas flow and fuel mixing, making the car labour and chug then you're doing it wrong, but more revs is almost universally less efficiency.
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