Are diesel cars suitable for city driving?

Car buying advice
Are diesel cars suitable for city driving? The Car Expert #AskTCE

Following on from previous articles about the differences between petrol and diesel engines, and explaining why your fuel economy doesn’t usually match the official figures for your car, The Car Expert looks more closely at the suitability of diesel cars for use in city driving.

One of the most frequent questions submitted to The Car Expert is “Are diesel cars suitable for city driving?”  The answer is… maybe!

A diesel engine generates its power slightly differently from a petrol engine, and usually yields better economy and load-carrying ability, albeit with less power and a slower response time. This is why buses and trucks usually run on diesel – they are big, heavy vehicles carrying large loads over long distances. But what about city driving? Does the extra cost of a diesel engine yield savings in running costs for urban drivers or those who only take short journeys?

Diesel in the city – fuel economy

Firstly, short journeys. Any engine is very inefficient when it is cold, so the first 15 minutes or so of any journey will not yield very good fuel consumption regardless of the advertised fuel economy of the vehicle. So if your journey involves a short commute to work or trip to the shops, you will get quite poor fuel economy in either a diesel or petrol car.

Secondly, stop-start driving. Even once your engine has warmed up thoroughly, it is still not operating efficiently if you are constantly accelerating, braking and sitting at traffic lights. And because a diesel engine tends to lag and be a bit more sluggish off the mark than an equivalent petrol engine, but stronger once it gets up and running, there is a tendency to put your foot down harder to get it to respond and then have to lift off or even brake again to slow it back down as it starts to take off over about 20mph. This sort of driving uses more fuel than smoothly applying accelerator and brake. It is certainly possible to drive a diesel smoothly, but it takes a bit of practice and constant anticipation. Meanwhile, sitting idling at traffic lights uses fuel regardless of whether its petrol or diesel, so you are simply wasting fuel with both.

Mechanical issues – the Diesel Particulate Filter (DPF)

Very new diesel cars (ie – built since about 2008) come fitted with a Diesel Particulate Filter (DPF). This device collects the black soot particles you see belching from older diesel engines, especially when the engine is cold. The DPF stores this soot until the filter unit reaches a certain temperature and then proceeds to burn off the soot. It still ends up in the atmosphere, but as much finer, invisible particles rather than ugly black smoke, and is less of a health hazard.

This is good, right? Well, yes, but… To get the filter trap hot enough to burn off the soot, the engine needs to have been running for at least 15-20 minutes and it then takes another 10-15 minutes to burn the soot and clean the filter. When DPFs were first launched into the car world, most people didn’t realise this – including the dealers who sold the cars – and so customers were unaware they even had such a device. If the driver does not regularly (ie – about once a week to once a fortnight) go for a drive of at least half an hour, the filter trap clogs up. In addition to not filtering the diesel soot properly, continued or repeated clogging will eventually destroy the filter, requiring a very expensive replacement.

So, if your regular use of your car does not involve a regular drive of 20-30 minutes, you need to make a special trip just to clear your DPF every week or two, which is hardly helping your fuel bills. Cars built since about 2012-ish usually feature better-designed DPFs and improved engine computer controls which allow faster and more efficient burning off of the soot, so it is now less of a problem than before, but it is still a problematic issue for dealers who have to deal with irate customers objecting to paying hundreds of pounds to replace their DPF when they weren’t made aware of it. This is even more of an issue for used car buyers who have almost certainly not been given a proper explanation by the dealer and consequently are more likely to run into trouble.

Misfuelling – filling up with the wrong fuel

One other hazard is misfuelling, and it happens a lot more often than you’d think – according to the AA, 150,000 people do it each year, or once every three-and-a-half minutes! Putting diesel fuel in a petrol engine is very bad news, and putting petrol in a diesel engine is even worse. When switching from one sort of engine to another, such as when you buy a new car or in multi-car households, it is an easy mistake to fill up the tank with the wrong fuel. Damage caused by mis-fuelling is not normally covered by warranty, so you could be up for thousands of pounds if the engine has been damaged. Even if you don’t destroy your engine, it is still an expensive and time-consuming exercise to have the car towed away, drained and cleaned out before you can drive it again. This isn’t a problem of diesel engines per se, but if you are considering switching from a petrol car or already have another petrol car in the household, it’s worth keeping in mind.

Summary

All of the above suggests that buying a diesel car for mainly city driving is not a great idea. However, it also depends on your overall mileage and how much load (passengers, luggage, trailers, etc) you are putting on the car. The very broad advice usually given around the industry is that an annual mileage of over 10,000 miles/year over 3 years is about the threshold for choosing a diesel car over a similar petrol one. However, it also depends on the type of car you are looking at, how long you’re planning to keep it, what sort of deals you can get on one or the other, and so on.

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Recommended Reading:

Fuel economy: petrol or diesel?  “Should I buy a car with a petrol or diesel engine?”  Well, there’s no simple answer; it depends on a number of factors.  In this blog, we explore this in more detail.

Fuel economy: Real-World vs. Official Figures. One of the biggest complaints drivers have is poor fuel economy, or more specifically that the car uses a lot more fuel than the manufacturer’s figures suggest.

Premium diesel petrol – do they actually work? The Car Expert answers a reader’s question about the value of premium fuels.

Are diesels any good for urban driving? Ask The Car Expert

Stuart Masson

Stuart is the Editor of The Car Expert, which he founded in 2011, and our new sister site The Van Expert. Originally from Australia, Stuart has had a passion for cars and the car industry for over thirty years. He spent a decade in automotive retail, and now works tirelessly to help car buyers by providing independent and impartial advice.

37 Comments

  1. Does the car expert have any comments regarding Mazda CX5 diesel engine that does not require a DPF due to its lower compression ratio. Having yet driven one I found no sluggish response . Is this something that European car maker are also looking at?

    Reply
    • Stuart Masson

      Hi Fred. Thinking of replacing the Passat?

      I haven’t driven the Mazda CX-5 and I’m yet to see specifics of their engine. However, their SKYACTIV program which aims for greater efficiencies across the board is very thorough, and apparently the new CX-5 is a very good car.

      Cheers, stuart

  2. Hi Stuart,
    Yes am thinking of Passat replacement. Although it is now driving beautifully I’ve lost faith due to the problems it’s given me. The extra warranty VW gave runs out in September.
    Although I’m used to the delay of the Passat, the CX5 does this so much better and more like my previous Mazda 6 but with much better fuel economy.
    Although diesels are still low in numbers compared to petrol in Oz the CX5 and future Mazda models should give the European vehicle manufactures some more competition.
    By the way love your site and your insight with vehicles and all things automotive even though it’s for a different audience . Keep up the great work, will be visiting your site regularly.

    All the best, Fred

    Reply
  3. DPF is a scandal that car makers need to own up to. I had all sorts of trouble with my VW because nobody told me what a DPF was or how it worked. When the light came on I called my dealer who told me it was fine and just meant that the car was cleaning the filter out, so I kept driving. After another few days the car came up with big warning messages telling me to stop immediately, which was bad timing as I was in traffic in the rain. Car had to be towed to the dealer and they tried to charge me £800 for a new filter! Well I can tell you that s*** hit the fan and after a week of arguing VW agreed to replace it for free. Still makes my blood boil to think of all the hassle they put me through.

    Reply
  4. How fast is engine technology changing and how long does information like this stay accurate? It seems to change so quickly its hard to know how relevant articles on the web are if they were written two years ago

    Reply
    • Stuart Masson

      The technologies change relatively quickly, but the principles tend to hold for longer periods. Both petrol and diesel engines are still improving, so newer cars tend to be cleaner and more efficient, as well as being more powerful, than older ones.

  5. There is so much stuff on the web that contradicts other stuff. i read your article here and it sounds like good advice, then i read something else which says the opposite. Its hard to know who to believe and its not helpful.

    Reply
    • Stuart Masson

      Hi Ray. It depends a lot on your specific circumstances. The principle of ‘horses for courses’ very much applies to the suitability of a diesel engine for your driving situation. It can be difficult to know which information is best for you, but that’s mainly because articles and blogs will always have to be reasonably generic to appeal to a wide audience. When helping clients choose a car, I discuss their requirements and specific driving circumstances in extensive detail, to make a recommendation that’s best for them. Cheers, stuart.

  6. I love the CX-5, the interior space is amazing!

    Reply
  7. Hi Stuart,

    I am planning to buy an used BMW 1 series (2008, 2009 or 2010 model) that would be put into use only during the weekends (approx 25-50 miles of usage per week) and maybe some long drives (e.g. vacation once in quarter). Would you suggest a petrol or diesel version? I am not worried about the buying price, I am more concerned about the vehicle maintenance and repair costs?

    Reply
    • Stuart Masson

      Hi Jo,

      Based on your overall mileage, I’d suggest you start by looking at a petrol 1-series. You’re not saving anything in overall spending by going for the diesel, and the BMW petrol engines are lovely things. Maintenance and repair costs are likely to be very similar for BMW petrol and diesel engines, and for weekend driving the petrol engine would be more enjoyable.

      Thanks,

      stuart

  8. Hi Stuart,

    I’ve owned a e46 325i (sold), a 2008 128i (wife’s car) and a Honda Accord Euro petro (Acura TSX) which is my current car. The Accord Euro petro is a good reliable car, but it’s so boring to drive compared to the other cars I own or have owned.

    I’m currently looking to purchase a 2011 e90 335d and I drive around 20,000km per year or 13,000 miles per year. I drive daily about 55km or 33 miles, 15 miles each way (60 urban/40 freeway).

    If I purchase the 335d I’d removed the DPF and use a downpipe and firmware mods to the ecu.

    Do you think I would be better served by a petro 335i? I like the power band of the 335d, but don’t know if it’s right for my driving habits.

    Any feedback is greatly appreciated.
    Bruce

    Reply
  9. Hi Stuart,

    Another comment from the land of OZ. I finally replaced the Passat last November for a Mazda CX5 Max Sport Diesel. So far so good! Handling great, pickup from start leaves the Passat way behind!!!, smoother automatic and of course higher seating view.
    Overall the Mazda does everything better than the Passat (I’m sure the current Passat has possibly improved). The Germans do know how to build quality into cars but at the cost of reliability and $s to repair (especially here down under – costs may not be an issue in the UK?). Fuel consumption is nearly the same even though the diesel in OZ only comes with AWD that adds another 90kg to the weight of the car.
    Have you had any comments from the UK?

    Reply
    • stuart

      Yes, the CX-5 has received excellent reviews from both journalists and owners everywhere. the only reason it doesn’t do better here in the UK is that the Mazda brand is very small here compared to there in Australia, so it’s not even on most people’s radar.

  10. Hiii

    I think Petrol cars are more efficient in city than diesel cars

    Thanks

    Reply
  11. we are senior couple & are thinking of buying Mercedes Benz class B180 & we do 5,000 to 7000 mileage per year, would you recommend we go for Petrol or Diesel . Any feedback is greatly appreciated.

    Reply
  12. Hello Stuart,

    I am in a bit of a dilemma right now and could really use your advice.

    I am thinking of buying a Ford Focus mk1, but am not sure whether to go for a petrol or a diesel engine. I plan to use it for a commute which is some 4 miles one way in a big city and weekend trips to the countryside, so most of my trips will be short – but most of the mileage may well come from those weekend trips. With cars so old, there is practically no difference in price between petrol and diesel versions, so this isn’t a factor. I would save on fuel bills with a diesel, but would it come at a cost of excessive engine wear? Are there any ways in which the wear can be reduced – apart from the obvious like e.g. driving as smoothly as possible, which I tend to do anyway?

    Thanks,
    MigrantWorker

    Reply
    • stuart

      I’d suggest the petrol is probably a better bet since the majority of the usage (although not necessary in mileage terms) is short-distance commuting. Have a read of this article comparing petrol and diesel engines – I wrote it three years ago now, but it’s still relevant today.

    • Thank you for your response. I have read the article that you pointed me to, and what I took away from it is this:

      For a cheap old car which is not going to do many miles, the engine choice is secondary compared to the general condition of the car. The repair costs can easily consume all the savings from an optimal fuel choice, and more.

      And by cheap, I mean up to 1000 pounds.

      Is my reasoning correct?

    • Stuart Masson

      Yes, entirely correct :)

  13. Hi

    I do around 250/300 miles a week this costs around £55/60 a week in fuel I drive smoothly using my car for delivers its mostly town driving, I aim to reduce my petrol bill by half but am unshore if a 1.6 diesel fiesta econetic 2011 with 20000 miles or a 1 litre Suzuki alto 2013 with 10000 would be best suited any advice?

    Thanks

    Reply
    • Stuart Masson

      Hi Danny. Of the two cars you described, the Fiesta is likely to offer much better performance than the Suzuki. It will depend on what you are used to driving and how much weight you are carrying. The Suzuki will have to work harder to match the Ford's performance, so if you put your foot down hard or are carrying heavy loads, the Ford will probably be the better vehicle. it's probably also larger than the Suzuki, which may be important for your deliveries. If you don't need the performance or space, the Suzuki is probably fine.

  14. This article was really helpful, I've always considered buying a diesel car but I do a lot of short journeys around the city so was never sure if it was right for me, but this has cleared a lot up, thanks!

    Reply
  15. hello my name is keegan , i am really lost between 2 cars the Peugeot 3008 1.6 diesel and the Suzuki s -cross 1.6 petrol , and both are automatic cars
    am trying to get a new car and now i have Kia Venga petrol , i don't drive a lot of miles at all ,
    in 3 years i put less than 11000 miles on my Kia car and most of the time i drive locally and so can any one advice me and tell me what is better car for me the Peugeot 3008 1.6 diesel or the Suzuki s -cross 1.6 petrol automatic ,
    i am disabled and i do need the car to go to my doctors and hospitals and for shopping also , and maybe in the summer i drive out side the city between 3 and 6 times to other city ,
    so please can you tell me what is good to get , diesel or patrol ??
    i am only worry about the filter problem with the diesel ,
    because sometimes i don't even drive the car for 2 or 3 days ,
    thank you for your help

    Reply
    • Stuart Masson

      Hi Keegan. If you are not doing a lot of mileage, then you don’t need a diesel. In which case you should choose whichever car suits your needs or is more comfortable. For more information, have a read of our comparison between petrol and diesel cars.

  16. Hi Stuart!
    Wè are looking to replace our diesel car a Ford Cmax with a Nissan Note, I only drive in the city and go on the motorway every fee months.
    What kind of family car would you recommend for a family of 5? Q

    Reply
  17. I have just stumbled on this site…Just bought myself a 57 plate Audi A8 4.2 V8 twin turbo diesel. Most miles I will do will be circa 5000 miles, please can you advise how best to run it as I never knew about having to run long miles to avoid large repair bills.

    Reply
    • Stuart Masson

      Hi Arn. If your diesel particulate filter (DPF) is getting full, you will get a warning light (usually yellow). Basically this means you have take the car for a fairly spirited drive for half an hour or so, so it can burn off the built-up particles. For the vast majority of people, this light will rarely appear and a brisk drive will see it disappear. If you don’t acknowledge the warning light and give the car a good workout, the filter will continue to absorb particles and will become clogged. You will get a more serious warning light and message (usually red) telling you to report to the dealership or even pull over and stop driving (depends on the car, not sure what the A8 will tell you). This then means the dealer has to manually clean out the filter, which is an expensive process and can damage the filter. It’s also not covered by any warranty.

      In short, it’s not usually too much to worry about. Plenty of people will never see the warning light because they spend enough time driving at a reasonable pace for a reasonable time that the soot can all burn off under normal driving circumstances.

  18. Dear Stuart,

    it seems like you are the one to answer my question. I would like to buy a Nissan X-Trail from the previous generation (say around 2010). I drive approx. 10000 km (~6000 miles) per year, mostly city driving plus some longer trips. Optimally, I should go for the petrol engine and an automatic transmission, however:
    1) Petrol X-trails are almost non-existent around here (Hungary), even with manual transmission.
    2) I am not sure how well the petrol engine fits this heavy car. (I would not do a lot of towing.)

    My questions are: can I go for the 2.0dCi engine with mostly urban use? My daily commute is 10+10 kilometers. Is there a DPF in this engine? Is it very brave to buy a well-maintained specimen but with around 100000 miles in it?

    Your answer would be greatly appreciated.

    G

    Reply
    • Stuart Masson

      Hi G. The diesel version is certainly more popular, so you will have much more choice when looking around for a car. As long as you are doing the occasional longer drive, the DPF shouldn’t cause any problems. It’s important to note that if you do get the initial warning light, you do take a it for a decent drive (probably 10-20km) to allow the DPF to burn off the accumulated soot. Most DPF problems come from owners not bothering to do this.

  19. Hi Stuart. I live in a busy city centre and drive 14 miles to an equally busy near-by town. Half of my journey is spent doing around 70mph pretty consistently and the other half is stop start- traffic and lights. Currently I am driving my husbands 2 litre petrol BMW 1 series as I recently wrote off my ancient Fiesta. I know his car isn’t right/costing me too much. I’m also a pretty heavy footed driver. I like the idea of another petrol Fiesta (1.2l) but would consider another car. Any suggestions? thank you in advance!

    Reply
  20. Just found this article after an online search. Thank you for corroborating what a car dealer told me today about the minimum mileage needed to maintain the DPF – I test drove a diesel elsewhere and not a word was said about this issue! Even with a 30km round trip every day for work I would still be doing less than was really good for a diesel engine, so I’ll be sticking to petrol!

    Reply
  21. I`m thinking of buying a BMW 116D 5D Sport (1st registered 1st Nov 2013) giving my mileage will be 7000 per annum will I have problems with the DPF. Journey time into work is approx. 30mins, I though this BMW diesel engine was one of the best. First time buying s diesel by the way, always had petrol.

    Reply
    • Stuart Masson

      Hi Tony. It will depend on the specifics of your drive route, but you probably won’t have any DPF problems with a 30-minute daily drive – especially if you have other variations in your driving from time to drive.

  22. Thanks Stuart, journey is a mixed bag. A little doing 50mph but mostly stop start urban / town driving. I think I`ll switch off the stop / start facility in order to maintain engine temperature which seems to go against why the facility is there. Just came back from the local BMW dealer, (who was disappointed I wasn`t buying a car off him), & assured me there are NO problems with DPF no matter how you drive. I think I`ll still go ahead as it`s a good looking car for the price, but typical of the internet you read all the bad stuff & this issue about DPF rang alarm bells. Thanks for the feedback

    Reply
  23. This article is very helpful as related to other article similar with this topics. According to me diesel cars are well fit for city journey. This is because cost, power full engine and easy available spare parts. Automotive Aftermarket is always available with best Auto diesel care products for your vehicles.

    Reply

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