I was just idly looking at some CashCows on autotrader. Looking at 4x4 equipped models, it appears that the 2.0dCi diesel has only slightly better fuel conusumption figures (better by 2mpg on the combined cycle) than the 2.0 petrol. I expected the difference to be greater. Should I have?
Also, the 2.0dCi's CO2 figure is 208g/km, whereas the 2.0 petrol's figure is lower, at 198g/km. Not only does it seem odd that a diesel engine of the same size as the petrol verison emits more CO2, but to manage that whilst demonstrating better fuel consumption seems contradcitory.
Am I missing something here?
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Think they may have their figures wrong - comparing like with like (bear in mind the QQ has 2wd and 4wd versions) the diesel always has lower emissions, and although What Car don't give the average fuel consumption (they seem to prefer £s/100 miles), the fuel consumption is less as well, between £1 and £2 per 100 miles dependant on 2wd or 4wd.
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Because diesel has a higher energy content, if the fuel economy is the same as petrol the emissions will be higher, i.e. more CO2. That is, a diesel car managing 40mpg will produce CO2 of about 195 g/km and a petrol managing 40mpg will only produce CO2 of about 170 g/km.
This is offset by the fact that normally the diesel engine is so much more economical (when compared to same car with similar petrol engine capacity and power) so that the overall emissions are lower.
This must be an example where this is no the case. Are these cars with autoboxes? That usually hurts the fuel economy of diesel engines harder than petrols.
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The old diesels have lower emission line always tickles me, they have lower emissions of the things that those in power decided to test for ? primarily plant food for tax raising purposes. The other nasties that get kicked out are ignored ? it's no coincidence that inner-city asthma rates have spiralled since the average car driver has switched to diesel power. Much of the fuel consumption advantage is negated by the fact the fuel now costs at least 10% more than petrol in the first place ? as does the vehicle itself. You have to do pretty serious mileages before diesels make sense - even then if you're a motorway high mileage driver modern petrols are surprisingly fuel efficient driven like this. I tried in vain to explain all this to my 3,000 miles per year mate who insisted on a BMW 330D over it's excellent petrol cousin
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Have you checked the car by car on here?
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Hear hear!
Carbon dioxide is not a pollutant in the usual sense of the word. It is not a poison. The focus seems to have been lost and everything is being driven by Carbon Dioxide emissions to the exclusion of the real nasties.
I have a diesel car because its a company motor and the company decide what I drive. When I come out of that scheme in a year's time I will get a petrol car.
And as for choosing a 330d over a 330i petrol BM, well I despair. Sure the 330d is a fine car, but the 330i is so much smoother. I'd love to be able to justify a 6 cylinder petrol BM. I reckon you need over 15k miles a year to break even.
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Oilburner, yes both diesel and petrol cars are autos.
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Aha! There you go then.
In the real world, for two such engines with an autobox, long distance cruising in the diesel would probably be more efficient than the petrol, but the petrol may be superior around town.
My old S80 D5 with auto was great on the motorway, giving over 50mpg if driven with great care. Around town it could drop to less than 30mpg though, not much better than the 2.4 petrol!
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For what it's worth AV, I have a QQ Tekna 4x4 2.0 auto diesel. Over 10k it has achieved an average of 38.7mpg in mixed usage measured by brimming. Not fab in my opinion but seems about right for the class. My old Mondy estate 2.0 diesel manual with mega miles on it still gets 45mpg in similar usage. Coincidentally so does our Mk1 Ka 1300 petrol.
The QQ is nice, can't fault it in any way and it has been great in the recent weather but somehow it fails to excite. I still prefer the "feel" of my old faithful Ford for reasons I simply can't explain. If I could give it an anti-ageing pill I'd keep it forever. Might do that anyway......
;-)
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Humph. Just remind me does yours have the dreaded diesal particulate filter. i think you said yes at a previous post. It hadn't re generated.
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It does Brentus. I guess it must be working but I still have never noticed it doing so. It was serviced just before Christmas and given a clean bill of health then but I really wouldn't know. I was rather hoping to create a rooster tail of white hot flames behind me which would have been especially satisfying on Monday when a twonk in a Merc Sprinter was trying to get into my boot while we were both doing 50 mph on frozen snow !
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Are these cars with autoboxes? That usually hurts the fuel economy of diesel engines harder than petrols.
>>
The discrepancy between official and actual mpg is worse for autos, cars are tested in simulated conditions on a rolling road, this involves holding cars in certain gears at certain road speeds for certain periods of time. For autos this particular in-gear requirement is ignored and cars are allowed to change up at will. This means official mpg figures for some autos - especially BMWs - are better than the manual equivalent - in reality the cars aren't as fuel efficient.
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Good input everyone, thanks. I had always gone on the assumption that a 2.0 diesel would be more economical than a 2.0 petrol. Seems it isn't always the case. Live and learn.
Never assume, it makes an ass of u and me.
I'm highly unlikely to buy a CashCow, as they're still all pretty new and pricey, and I can't abide the high up, SUV styling. Not me at all.
If I switch to 4WD, it'll most likely be a Subaru Legacy or Forester.
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I didn't think they were me either. Still not sure to be truthful. All a bit too "Cheshire" in some ways. Dunno what that makes the Mondeo estate mind you....."Essex" maybe ?
But....in fairness the QQ is very very good. Bit of a moose in the looks dept. but really very good otherwise. Not majorly keen on the lecky steering but notwithstanding that a very relaxing and pleasant place to be. Just not sure that I want to be so relaxed just yet....
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PS is the diesel the same engine as fitted to the x-trail? Although Nissan have claimed to have fixed all the recurring turbo failure problems, can we be sure?
PPS I've driven a "CashCow" I loved it!
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I like the look of the QQ but, possibly wrongly, I didn't feel that it was as high as my Altea XL and I like a high driving position?
Also, Humph, whats your thoughts on the flexibility inside re putting seats down for big loads - IIRC the seats weren't that flexible in layout?
Wonder if the QQ+2 gives much more available space?
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I don't mind a high up driving position, one of our cars is a Touran. I just hate SUV/Jeep type styling.
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Loadspace would be more than adequate for most purposes Bobby but it doesn't come close to the Mondeo estate. Not that it's fair to compare it to that cavernous loadspace I suppose. Seats fold not quite flat. Acid test for me is that you can get three mountain bikes in the back of the Mondy without dismantling them and still have one back seat. You can't get one in the QQ without removing a wheel and end up with no back seat.
Having said all the above, I generally have the bikes on the roof anyway. It's a fine and good car and I should be more than grateful for it.
You know that feeling you got when you had a girlfriend everyone including your mum liked and thought you should marry but ............
Edited by Humph Backbridge on 12/01/2010 at 16:21
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Exactly, Humph - it just goes to show that there isn't (and shouldn't be) any logical basis for loving a person, or fondness for a car. With a car it's perhaps to do with expectations: the QQ does the job it's supposed to do (apart from rear seats not folding flat - how silly in a car that shape), but the Mondeo has gone the extra mile(s) for you, still reliable and good to drive after mega-mileage.
That may be part of the reason why Skodas always feature well in satisfaction surveys: you buy a car to do a job and it does it with more verve and enjoyability than you expected.
Going back to diesel automatics, the unavoidable problem is that, unlike with a manual, you step off from rest at 0 rpm, and you have to use plenty of right foot to get it up to the rev range where it's at its best. I get vigorous acceleration from my manual diesel from the start because (except in snow of course) you kick off with 1000-1500 rpm.
Edited by Avant on 12/01/2010 at 22:10
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Going back to diesel automatics, the unavoidable problem is that, unlike with a manual, you step off from rest at 0 rpm, and you have to use plenty of right foot to get it up to the rev range where it's at its best.
1. Engage drive (whilst holding footbrake with *left* foot)
2. Step on accelerator to 3,500 rpm (whilst holding still footbrake)
3. Release footbrake
Heats up the transmission oil so if your car doesnt have a transmission cooler / radiator i wouldnt do it too often on the one journey.
Done it once just to see how it goes. Like snow off a dyke in June was the answer :-P
Edited by CraigP on 14/01/2010 at 17:25
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Humph, thanks for feedback, obviously the Mondeo is cavernous but quite interesting to compare it to the Altea.
My Scenic had 3 individual seats that the backs could fold flat, or whole seat tumbled forward, or completely removed. I made use of all 3 options quite often.
I moved to the Altea which has standard 60/40 split and the backs only fold down, albeit quite flat, and the whole seat can be pulled forward to make more boot space. Occasionally I have had to try and put my hybrid bike in it and it wasn't easy.
But it sounds like the QQ is even less flexible?
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The cashcow is a very heavy car, some models are heavier than my xtrail, yes its the same 148bhp dci engine, which is now a renault engine, the old xtrail was a nissan engine.
As for the turbo, the new engine has a separate pump that cools the turbo, operated by temperature and will i understand run when the engine is turned of.
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