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RUBBISH Fuel Consumption - 8th gen diesel auto tourer

P

pauljdh

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Messages
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Location
Derbyshire
Car
i-dtec auto tourer
Until 2 weeks back I had a 2.2 i-cdti manual tourer which was returning 52-56mpg (indicated) without even trying.

I changed it for a 2012 2.2i-dtec AUTO tourer and in the two tankfuls Ive got through Im very disappointed at the fuel economy.

To make it a reasoned statement:

I buy the same fuel from the same garage
My journeys are identical in all respects (length, traffic, duration, time of day etc)
Both cars have immaculate 100% Honda SH.

So the indicated (car computer) figures are 54mpg (i-cdti manual) vs 36mpg (idtec auto).

Known differences

  1. manual vs auto
  2. DPF vs non-DPF
  3. i-cdti vs i-dtec
  4. i-cdti had a stage 1 tune from premier tuning. I claimed an extra 3-4 mpg after the map over

Allowing for the automatic gearbox loss, even allowing 8mpg, which would be excessive, the later generation car is significantly poorer in fuel burn - surely not something Honda intended?

So Im thinking,

  • FAHADS tune was more powerful in terms of economy than I allowed
  • The DPF is a big restriction and does nothing for fuel consumption (On Tues HH confirmed that my software is up to date and the filter is holding only 5g of soot)
  • The auto gearbox is poor
  • The 8th gen is a much heavier car
  • The computer on an i-cdti is optimistic or the i-dtec is pessimistic

but - the 7th gen used to outperform Honda's and .govs official figures easily whilst the 8th gen massively underperforms both.

I know I need to do a tank to tank calc but everything indicates things are much worse. Tyres are good etc, brakes not binding and nothing reportable on the car

As soon as Im settled with the car I want another economy tune and a DPF off (currently its been fine) which may help.

If it doesn't match the official figures from Honda Ill be taking it back for a look see, although it was serviced 3K ago.

Anyone agree / disagree, any comments or ideas? Those from auto i-dtec owners especially welcomed!

Really didn't expect to be going backwards with a next gen car (even allowing for an auto).


So, apples and apples - 54mpg-8mpg (auto)-4mpg (stage 1) = 42mpg for my i-cdti and Im lucky to get 36 on an advanced design. Somethings amiss.

Cheers

Paul
 
Just done the same move as you, but no remap on my 7th tourer, yes the 8th auto idtec seems a little heavier on the fuel front, but after that there is no comparison, I loved my 7th, but it was on 198,000 and I know it would go on for a good while longer, but circumstances demanded I go AUTO, and with this one I am more than happy, so smooth and plenty of grunt, will get back with some figures. With regard to the "computer" none on my 7th, and the one on the 8th seems a little too pessimistic, I work from fill up to fill up.

Just had a look at the puter av speed 40mph average mpg 40.5, I am having trouble believing both readings, as I had just done a fifty mile run in under the hour.
 
I bought a 59 reg 2.2i-dtec AUTO saloon and must admit I am disappointed in the fuel consumption, currently 37.1, that is over many 100's of miles, not sure of average speed. Much of my driving is around the doors with a 50 Mile run on a Friday and Sunday, and I do tend to drive like Miss Daisy............ :) :)

My previous car, an AUTO 2.7 Diesel Jeep, well we won't talk about that...... :eek: :eek: However, doing the exact same runs in a 1.6 diesel Citroen Grand Picasso with 7 seats, that NEVER returned less that 44MPG and when I did my longer runs at the weekend was over 50MPG.

The ironic thing is, when we bought the Honda I was looking for another Citroen, found a young Honda Salesman who took us out in the car and turned all our heads, he did such a good Job I had to inform his manager, as a Salesman in the old day's I know how much this means; oh and the car, Love it and the after sales service from the Honda garage is second to none, in my experience........... :) :)
 
The iDtec auto is more suited to long motorway runs, where I think you would get much better figures.

My 2.0 petrol auto does over 40mpg on the motorway and I average 32mpg around town semi-urban, plus I don't have any tractor sounds or DPF worries.

Paul, maybe consider returning the car for a refund under the Honda happiness return guarantee.
 
Guys this sounds normal for the Auto box.
I had one as a courtesy car a few years back from HH and this was the MPG I was getting
 
Yep I think if you want economy the manual geared iDtec is the way to go, but manuals seem to have some clutch and DMF problems at high mileage.

Petrol or diesel an Auto box always robs you of at least 10% economy, maybe more.
 
richsprint said:
Yep I think if you want economy the manual geared iDtec is the way to go, but manuals seem to have some clutch and DMF problems at high mileage.

Petrol or diesel an Auto box always robs you of at least 10% economy, maybe more.
Click to expand...
There speaks a man who knows, Wanna buy my 2.0 Auto??
 
I've just done a 1k mile round trip with our 2010 i-Dtec auto 4-door from home in the Limousin area of France to the Med coast at Sete with a lot of mountains both ways as well as some motorway miles, not to mention running around with 4 adults in between. Fuel consumption according to the computer was 52mpg overall. Sounds OK to me - I still think the diesel auto is the best transmission I've ever had. If I could be bothered I'd work out the fuel consumption from fill to fill because I don't think the computer is very accurate.
 
mikey77 said:
I've just done a 1k mile round trip with our 2010 i-Dtec auto 4-door from home in the Limousin area of France to the Med coast at Sete with a lot of mountains both ways as well as some motorway miles, not to mention running around with 4 adults in between. Fuel consumption according to the computer was 52mpg overall. Sounds OK to me - I still think the diesel auto is the best transmission I've ever had. If I could be bothered I'd work out the fuel consumption from fill to fill because I don't think the computer is very accurate.
Click to expand...
makes complete sense to me.
IMO the current Honda F1 engine is more reliable than a couple of "spot checks" on the on-board computer. Also one fill-up does not a full story tell. It is possible that the engine was doing a DPF regen on that particular fill-up segment. With a diesel, particularly one with a DPF, you need to record all the fuel that you have put in over at least a thousand miles in order to be certain.
 
edgeoftime said:
There speaks a man who knows, Wanna buy my 2.0 Auto??
Click to expand...
Not for sale any more as I've realised it worth keeping, as its reliable and economical!
 
richsprint said:
The iDtec auto is more suited to long motorway runs, where I think you would get much better figures.

My 2.0 petrol auto does over 40mpg on the motorway and I average 32mpg around town semi-urban, plus I don't have any tractor sounds or DPF worries.

Paul, maybe consider returning the car for a refund under the Honda happiness return guarantee.
Click to expand...
Thanks I thought about that but I love the car apart from that and I think there has to be a fault with it to instigate a change - you can't just change you're min can you?
 
richsprint said:
Yep I think if you want economy the manual geared iDtec is the way to go, but manuals seem to have some clutch and DMF problems at high mileage.

Petrol or diesel an Auto box always robs you of at least 10% economy, maybe more.
Click to expand...
thanks, 10 % would only account for 4-5mpg.....
 
brett said:
Guys this sounds normal for the Auto box.
I had one as a courtesy car a few years back from HH and this was the MPG I was getting
Click to expand...
Thanks its just that its miles off the official figures, and Honda own too - I bought the car aprtly after comparing the published figures with 2 other cars - it was still the worst , but only by a couple mpg. Are Honda misleading us?
 
Just a thought Paul has your car had the ECU update that was on a TSB a wile back.
Worth asking the dealer to check
 
obviously Auto will rob you of some economy and is more affected by driving style if its a slush box. The 7gen will not do 50+ unless you sit at 55 flat road, no bends. I would say the 7th gen is more in the range of 40-45mpg.

only reals way is too work out over actual tank fills.
 
My 5 speed 7th Gen Diesel Tourer averaged 48mpg over my 60K mile ownership. My 6 speed 8th Gen Diesel Tourer is doing about 52mpg over my 4K ownership (to date) . That's from fuel receipts and the odometer, not the computer. I'd say overall considering the number of gears, the weight, aerodynamics, rolling resistance etc the manual cars are pretty closely matched with the 8th possibly just having the edge (given that my routes and driving style have been near identical across both cars).

I think you need to do some fill to fill tests to be sure as sounds like (maybe) one computer was a bit optimistic and one a bit pessimistic. I ***ume you have standard (circumference) wheels on? If you have odd sized rims on your speedo / odometer will read incorrectly.
 
I've just done a tank to tank, same nozzle, at same Shell garage etc and calculated mpg is 37.1.

The car computer indicates 36 so good correlation but both are too low for my liking. Thats A38 / A6 at 40-60 mph and easy town driving.
My i-cdti, over 50 K miles, low 50's, all day long on same conditions, although as I said it was a 6 speed manual.

Its not the absolute value that hacks me its the published figures are so misleading....
 
brett said:
Just a thought Paul has your car had the ECU update that was on a TSB a wile back.
Worth asking the dealer to check
Click to expand...
Think so Brett, I was at Holdcroft on Tuesday having worn drive shafts changed and they confirmed I have the latest software (certainly they confirmed the dpf software was up to date, I ***ume thats part of the ECU S/W?)
 
mikey77 said:
I've just done a 1k mile round trip with our 2010 i-Dtec auto 4-door from home in the Limousin area of France to the Med coast at Sete with a lot of mountains both ways as well as some motorway miles, not to mention running around with 4 adults in between. Fuel consumption according to the computer was 52mpg overall. Sounds OK to me - I still think the diesel auto is the best transmission I've ever had. If I could be bothered I'd work out the fuel consumption from fill to fill because I don't think the computer is very accurate.
Click to expand...
thats impressive!
 
I have an idtec auto estate and do a lot of long runs and over the last 45k miles I have averaged a steady 40-42mpg. I am no slouch though do not hammer it through the gears. I expected about 45mpg at a push but hey...... nothing is what it seems. I never rely on the trip computer, I always work it out from brim to brim.
 
It could be worse chaps, I'm lucky to see 15mpg out of my diesel auto...






















;)
 
Just done a brim to warning light, 40.5 MPG, AVERAGE SPEED 47 MPH. Will see how the next set of figures compare. Do I really care though? NO
 
A new DTEC auto owner here!

Mines showing 34.1mpg at the moment.

Like others have said I would t trust the onboard computer but it doesn't seem to be to far off.

Quite poor really. I enjoyed late forties/ early 50's in my previous 54 plate c200 2.2CDi auto.
 
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