I`m not sure cold, stop start Diesel gets its merits displayed in the official fuel consumption figures.
We often say or hear said, "you have to do over 12,000+ miles before diesels worth it"
It seems to me most of the cars being discussed are bigger vehicles where perhaps use is being made of the power available.
But what if you`re considering a small diesel and the official figures only show a small MPG difference? It would be easy to think, `I`m retired and doing under 10,000 miles a year I need the petrol`.
Thought I would try it out this AM on a typical 6 mile trip to the shops.
Temperature, just below freezing, ice on the screen.
Start and drive straight off, 20mph for a few hundred yards, then onto an urban city road leading out of town. Stop twice at lights, car has heater blower and headlights on as I climb, still in 3rd gear, up onto a ridge, 1 mile further at around 400feet altitude.
At this stage, the temperature gauge is not registering and computer showing 47MPG.
Onto a motorway for two miles running at 60MPH, onto duel carriageway, halting and queuing at lights and roundabouts. 30MPH zone and enter the city from the other side finally arriving at my destination at the same altitude as starting and the temperature gauge still not quite at `normal`.
The computer is showing 63.5MPG for the small common rail diesel.
We got only 31MPG for a loan petrol car over the same journey, no doubt having to run a rich mixture.
This must be a typical journey for many people in winter, in particular those retired or running children around to school etc.
But why do you rarely hear of the big fuel savings on cold, short journey, stop start use with diesel?
(Diesels driven care that is and not booted forward at every gear change with maximum torque)
Could it be that the official fuel consumption tests flatter Petrol? and what would the difference be if the typical short, still not up to temperature run above were introduced as a measurement? where Petrol has to run rich and waste its fuel.
Regards
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But to temper that (and I'm not sure that mirrors my experiences), diesel cars take a lot longer for warm air to come out of the blower and are the engines/gearboxes are very rough when cold compared to petrol engined vehicles.
If all I was doing was short stop journeys, I'd have a petrol every day. That way you have a heater that works and a refined engine. Due to the limited mileage a stop start driver does, who cares about MPG figures? A difference of a pound a week just isn't worth it in my opinion.
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Isn't the Urban consumption figure a good comparative guide? It's based on cold start, short distance in traffic.
Everyone will get different consumption to the Urban figure because their driving style and conditions are different to those prescribed in the test.
Going back when we had urban (from warm) / 56mph / 75mph I used to ignore the 56 figure but the 75 was a good guide to motorway cruising consumption and the urban at least gave a clue when in traffic.
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I agree. For stop/start work a diesle is great.
Rough when cold? Get a decent non VAG one.
Heater? Yes: takes 2-3 miles for Yaris heater to warm up. I wear gloves. Solved.
SWMBO's 106 D averages over 50mph with an average journey length of 1 mile. And it still runs after 14 years.
As it's not CR , heater is warm in 1 mile.
People who drive petrol cars regularly in town are throwing ££s out of the exhaust.. but I don't care:-)
madf
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Our MoOndeo 03 TDCi 130 does a lot of cold start-stops. At the moment it is getting about 35mpg. The temp gauge never moves off cold. Heater is warm quickly as I guess it is an auxilliary one.
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>>>Rough when cold? Get a decent non VAG one.
Bull manure.
You can't beat a VW diesel, ask my missus she's driving my Passat while her Focus is in dock.
A diesel is much better for low milage journeys than a petrol. They are not on choke, so don't wash out the bores. The fuel consumption on diesels is much better than petrol, our Escort petrol did 300 miles on a tank, the Focus TDCI before it croked did 450miles per tank.
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My Octavia VRS TD gets pretty poor mpg while cold. If I'm just going into town (about 3.5 miles each way) I'll get at best 35mpg for the trip.
Whereas if I'm driving 100 miles + my average will be over 45mpg.
And it definitely does take a longer time for the cabin to warm up!
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None of this matters becuase the problem is that 4 cylinder diesel engines are noisy, rattly, vibrate the whole cabin, sound rubbish and are slow.
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None of this matters becuase the problem is that 4 cylinder diesel engines are noisy rattly vibrate the whole cabin sound rubbish and are slow.
Vibrate the whole cabin? Slow? Sound rubbish? When were you last in a modern diesel car?
I'll have to take you out for a ride in my Octavia VRS TD... It has a very nice growl when you accelerate hard. And boy can it accelerate hard..... ;-)
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Vibrate the whole cabin? Slow? Sound rubbish? When were you last in a modern diesel car?
Yesterday, when I drove the 530d. Which was nice.
But the last 4 cylinder one I drove was a 118d. You could feel the dashboard vibrate a tad at idle. You could hear the engine. Get outside, and it sounds like a minicab. Foot down and it goes nowhere.
Just why? Whats the point? If you do low mileage around town - as this thread is about -
the difference between diesel and petrol won't give you noticeable savings so enjoy the silence and smoothness of a nice petrol engine.
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OK MichaelR.
I do about 20k miles per year, the vast majority long motorway journeys. Diesel is an unbeatable proposition for me. For the economy, the durability, the residuals and the driving performance.
So the 118d vibrated the dashboard? My Octavia doesn't. My wifes Citreon C8 HDi doesn't. The last diesel I car that did was a Citroen Visa of early 90s vintage.
Maybe the 118d was faulty? Or maybe they are just badly made? I wouldn't judge all diesels from it.
And noisy when you stand outside it? I tend to be sitting in mine when driving it....
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So the 118d vibrated the dashboard? My Octavia doesn't. My wifes Citreon C8 HDi doesn't. The last diesel I car that did was a Citroen Visa of early 90s vintage.
Are you honestly telling me there is no noticeable shake in the entire car when waiting at the traffic lights? Honestly?
Maybe the 118d was faulty?
With 1000 miles on the clock?
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Are you honestly telling me there is no noticeable shake in the entire car when waiting at the traffic lights? Honestly?
Yes.
>> Maybe the 118d was faulty? With 1000 miles on the clock?
So newer cars can never be faulty?
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"Are you honestly telling me there is no noticeable shake in the entire car when waiting at the traffic lights? Honestly?"
Never even noticed it in my Berlingo, nor wife's Xantia, nor previous versions of both. In fact, I doubt it happened in the ancient BXs we had.
Didn't one of the old ads for BMW diesels show a 10p coin balanced on the engine to show how little they vibrated??
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Phil
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Exactly the same experience as PhilW with a non vibrating 205XLD shoved in the mix for good luck.
Ahead of the quieter cabin and better real world acceleration I got 40mpg 27/7/365 from my diesel BX. Lucky to get 60% of that in the previous petrol version - and if the thing didn't stall at the end of the road then it would when I waited at the narrow canal bridge.
Edited by Dynamic Dave on 17/12/2007 at 19:50
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But to temper that (and I'm not sure that mirrors my experiences) diesel cars take a lot longer for warm air to come out of the blower
What you save on fuel, you spend on thermal underwear, a thick jumper, and a good quality ski jacket!
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Which veehickle are you driving, O oily one?
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Mk2B Punto with the 1.3 multijet diesel.
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Just why? Whats the point? If you do low mileage around town - as this thread is about -
the difference between diesel and petrol won't give you noticeable savings so enjoy the silence and smoothness of a nice petrol engine.
i have to ask why so many taxi fleets are diesel and spend all their time doing short journeys in trafiic?
Maybe they are missing out an economical argument in favour of petrol?
Actually I think its because diesel engines are ideally suited to this type of journey!
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Books can and have been written on engine design and characteristics.
Two factors make a diesel the undisputed winner for town/short journey duties:
1. Diesel fuel does not need to be vaporised to burn it in the engine. The latent heat of evaporation does not have to be sourced as additional energy and additional fuel (choke in old money) is not needed with a cold engine to compensate for poor vaporisation.
2. A diesel does not run on a constant air/fuel ratio and is hence vastly superior in terms of specific fuel consumption at part load. A diesel will idle at 50:1 air:fuel and can run usefully at low demand at 25:1.
My Skoda Superb has 3 additional glowplugs in the cooling jacket, switched on by the ECU if the alternator demand permits. It warms up pretty rapidly.
659.
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Just why? Whats the point? If you do low mileage around town -
i have to ask why so many taxi fleets are diesel and spend all their time doing short journeys in trafiic?
Becuase they do high mileage around town not low mileage?
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659 put it better than me but,
town, traffic, short or long journeys diesel is better than petrol by far.
petrol is (was, probably) better for acceleration, power, comfort, not for economy or town running.
I put was, because diesels are fast catching up. Still a petrol man myself though, but dont dismiss diesel. It has its place.
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I've driven over 100,000 miles behind VAG diesels and they never gave any noticeable dash vibration at idle, and were quieter at M-way speeds than comparable petrol. The 118 must have been an aberration. But petrol engines, which only start producing power at 4000, and need more to get a move on, are anaemic in comparison. I prefer the deeper, bass register of the diesel to the boy soprano of the gas engine:)
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My Rover 420 diesel, despite being a clattery old hector, is giving an easy 53 mpg average and even with an hour crawling along the A14 in rush hour, still only dipped to 49mpg.
You always get the feeling I think with petrols, that they drink fuel faster than a diesel when you press on, perhaps because you need more revs etc, maybe its just psychological.
Oh and ya know what, I rather like the noise from my L-series - its loud enough that I can tell when its running right but at cruising speeds its more than quiet enough.
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A petrol sounds like a Eunuch. Yes. I suppose it's just as steam trains sound better than electric trains.
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Ahem, stop start and short work commute for SWMBO about 28 to 30 in the hilux, which i dont think is bad for a planet destroyer (just putting my hair shirt on) driven by a flyer.
To be honest over the years (and i've run diesels for a lot) i would say there hasnt been a great difference between stop start and distance consumptions of the various diesels i've owned, but the petrols varied widely.
The 124 merc 300d used to to about 35 regardless of how it was driven, my sons toledo 110 does about 45 regardless. (his impresa about 16 to 22 and we all know how thats driven).
For engine sounds i dont think much could beat the 'deltic' (certain age)
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I wouldn't be without my V6 petrol for the stop start town work, I needed to nip past a queue of cars during a short break in a bus lane today, foot down in the V6 resulted in a satisfying roar of power that blasted me up to the red line in second around a roundabout and past about 5 cars before the bus lane reared it's ugly head again. :-) (Doctorchris - it's the one on the A690 next to Maccy D's)
If I'd done that in a diesel I'd have had to change gear which would have been a big no no given that the wheels were also spinning slightly (TCS off) during this manouvere as they struggled to put the power down.
The whole episode possibly removed between 20 and 30 seconds from my journey and gave me a huge grin at the same time. That's worth 22mpg to me. :-)
Oh, and on the disel argument, my dad's CLK is clattery and noisy until it warms right through, however, he does some much longer runs and I have to confess that once it's wamed through it goes like the clappers and is mated to a lovely autobox which removes the effort from driving altogether. So, I'll get myself a diesel as soon as I have a spare £30K to buy one!
Blue
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"For engine sounds i dont think much could beat the 'deltic' (certain age)"
Or that wonderful Commer lorry engine of the 1950s....
Talking about noise, all engines are louder when cold, including quite a few petrol ones. If refinement is the priority, you need 6 or more cylinders, which Michael is lucky enough to have in his BMW.
My erstwhile Mercedes B200 CDI had a ridiculously low idling speed of about 700 rpm which caused the whole car to vibrate, not just the dashboard. The VAG diesels I've had idle at 850-900 rpm which avoids this.
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I'm curious to know where people get these nice, smooth, nonrattly diesels from. All the ones I drive, and especially the 4 cylinder ones, sound like tractors at low speed. Except the VW 1.9TDIs, they sound like broken tractors. The diesels I drive, and that includes Audis, BMWs Fords, Mercs, Peugeots and VWs, are also unpleasant in town due to a lack of any torque whatsoever until the turbocharger has started spinning and the fact that the clutch always seems to to be heavier to operate than the petrol equivalents. Whenever I drive a Mondeo TDCI around Munich I frequently end up stalling it changing from 1st to 2nd gear whilst fruitlessly wating for the "stump pulling torque" to appear.
For me the ideal town eco car must be the Toyota Prius. It has genuinely high torque from 0rpm due to the electric motor, requires no gear changing and switches the engine off when stopped thereby cutting engine noise and exhaust pollution to zero.
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The diesels I drive and thatincludes Audis BMWs Fords Mercs Peugeots and VWs are also unpleasant in town due to a lack of any torque whatsoever until the turbocharger has started spinning and the fact that the clutch always seems to to be heavier to operate than the petrol equivalents.
I prefer 8 valve diesels, they seem to have more torque lower down. My Citroen C5 has a powerbox and gives excellent acceleration from little over tickover.
I hated the clutch of the 2003 Mondeo TDCI 130 I test drove, it was too eager and the engine had no low down torque. You can't beat a well designed diesel for crawling urban traffic as you can crawl along at 5mph in 1st or 10 in 2nd without having to press the accelerator pedal.
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My Rover doesnt have a heavy clutch. Not only that but you can quite easily stick it in 3rd gear and lift the clutch progressively without touching the gas pedal.
Ive not driven many modern diesels that you can try that in as the revs always drop so quickly. Even my mums V6 Hyundai cant so it and that has loads of in-gear pull.
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Neither of my two diesels will do more than mid-high 30's in pure stop/start conditions. The Mondeo does 45-46 out of town - I can coax 55 out of the Scenic, although 45 is more realistic. I've never owned petrol equivalents, but on previous experience, mid 20's is the best you can expect from a petrol engined large family car confined to town use only.
In refinement terms, the Renault unit is definitely noisier when cold than when warm, but this engine is never rough. Smooth at idle, and from inside the car, barely audible at all under 3,000 RPM. A very impressive diesel installation in NVH terms which is smoother and quieter than some petrol cars I've owned.
The Ford Endura DE lump was rough as a bear's backside when brand new and 140k doesn't improve it. It's crude and vibratory whether hot or cold, but really does sound and feel like it's on its death bed on cold starts. Also has a marked "hole" in its power delivery at the bottom end until it starts to warm up. I drove three and they were all the same. But 140k up and it doesn't even need oil top ups between 10k changes, so it's doing what I bought it to do.
Cheers
DP
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04 Grand Scenic 1.9 dCi Dynamique
00 Mondeo 1.8TD LX
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My Yaris diesel does not rattle or shake or vibrate at idel.
My BIL (whos drives a Merc W124 300D estate) was driven by me for 20 miles... only when he got out did he realise it was a diesel. Mind you a 300D is noisy)
Even when cold it just goes on quietly...
4 cyclinder diesels designed by people who are decent engineers can be good (that obviously excludes BMW as per MichaelR :-)
VAG diesels on idle are horrible noisy rattley vibtrating lumps.. NVH is built in.. :-)
madf
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Having used most of the newer diesels, I would agree that the VAG PD unit is not the smoothest, but in real use I doubt whether a casual passenger would notice. The smoothness is also rather installation dependent - the PDs tend to be at their worst when transversely fitted as in Golfs and their clones, but in my Passat derived Skoda Superb it's pretty good.
It most certainly doesn't rattle, shake or vibrate and it's acceptably quiet at idle and low speeds. At any speed above 20 mph apart from rapid acceleration, the engine noise is overtaken by tyre noise, then wind noise.
The crux of the matter for me was that (in generalised terms) I'd rather have a modern turbocharged diesel which works fairly well all of the time than an ultra-smooth job which works for some of the time.
I am not generally happy with the fuel system quality or the applications engineering of the common rail fitments on most other engines - especially non-Bosch installations.
The PD is still one of the very few IC engines which will comfortably out-perform a coal fired power station in terms of energy conversion efficiency....
659.
Edited by 659FBE on 18/12/2007 at 14:57
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The PD's refinement is generally adequate in my opinion, noise levels helped considerably by the fact that there's so much shove at low to medium revs that you never need to extend them much beyond 2,500 RPM in daily driving anyway.
At idle, the level of noise and vibration seems to vary between individual engines even in the same type of car based on the examples I've driven over the past 12 months. I've driven Golf 130's of the same age, spec and mileage that have varied enormously in NVH terms.
The Renault dCi engine is far sweeter with none of the deep rumble of the VW unit , but neither does it have that same crisp, muscular surge at low revs on part throttle that makes the PD130 and 2.0 140 feel so grunty in daily use. It also doesn't have the PD's stunning fuel efficiency.
Cheers
DP
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04 Grand Scenic 1.9 dCi Dynamique
00 Mondeo 1.8TD LX
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If you want a real noisy diesel try the VAG 1.4 tdi 3 cyl jobby that I've got in my SEAT. Really noisy at any start below 5 degress, and not that smooth till its warmed up. Its fine when upto temp though.
Currently driving: 2007 SEAT Ibiza TDi
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If you want a real noisy diesel try the VAG 1.4 tdi 3 cyl jobby that I've got in my SEAT. Really noisy at any start below 5 degress and not that smooth till its warmed up. Its fine when upto temp though.
Yep, I'll agree with that, I have a Fabia incarnation version of that engine, and its noisier than the 1.9 version I had before - but having said that I don't like silent cars, I prefer to know that when I put my foot down to go the engine is still running without having to waste time checking the rev counter! - and the £35 tax suits me fine.......
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My 306 1.9TD generally does around 37-38mpg on stop-start journeys, esp when cold and 45-50 on long runs. I have noticed a slight drop in the fuel economy in the cold weather of late, especially when I have been doing a lot of short journeys. That said, I have managed to squeeze 540 miles out of 57 litres on the latest fill, with two thirds of that being motoraway driving.
The old beast is increasingly disliking cold starts- have to hold the key in for a good 5-7 seconds to make sure the engine has started, with a plume of white/grey smoke which could easily be mistaken for a steam train! But after 15 seconds, it settles down, the smoke clears and all seems fine.
Martin
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"The old beast is increasingly disliking cold starts- have to hold the key in for a good 5-7 seconds to make sure the engine has started, with a plume of white/grey smoke which could easily be mistaken for a steam train! But after 15 seconds, it settles down, the smoke clears and all seems fine."
New glowplugs short sort that out
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Phil
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