BMW 320D Touring - Petrol vs diesel. Small estate - Telegram Sam

In response to a recent query you wrote: "If you can find a 2009 or 2010 with a chain cam diesel engine that doesn't have a diesel particulate filter then that could be your best bet. KIA cee'd 1.6CRDI SW or Hyundai i30 1.6CRDI SW both delayed fitting DPFs until they absolutely had to. In the future, such cars may be banned from any city centres, but you wrote A road and country lane driving so that should not be a concern"

Could you please explain why DPF's are such a bad thing. In view of the latest reports on diesel pollution you would think that these were very worth while.

More generally: I will in time have to replace my 2002 BMW 320 D Estate. It has been a reasonably dependable, practical but rather uninspiring vehicle. I would normally start looking for a diesel replacement (second hand) but not necessarily the same car - but would you now opt for petrol? At present I do about 9 K miles p.a. mixed town and motorway, and tend to hold on to my car longer than most owners.

BMW 320D Touring - Petrol vs diesel. Small estate - craig-pd130

Some makes of car seem to be more prone to DPF problems than others. I've had a Mondeo and two Volvo V60s with DPFs, and had no problems with the DPF implementation or rising oil levels, etc.

This is despite my patterns of use being entirely unsuitable for DPF-equipped diesels (8 mile round-trip commute to work, 70% of my driving short trips of under 10 miles in urban limits). So, based on my limited experience, Ford and Volvo seem to have robust DPF systems, compared to say, Mazda.

These are, however, lease cars so they go back after 3 years. I've no idea if my driving patterns are storing up DPF problems for the next owner.

BMW 320D Touring - Petrol vs diesel. Small estate - Cyd

Could you please explain why DPF's are such a bad thing. In view of the latest reports on diesel pollution you would think that these were very worth while.

You would and indeed they are, BUT they have a limitation that when used for modest mileage and short journeys they are extremely prone to blocking up requiring expensive remedial work. In other words, the sort of driving most private owners do.

Hence the recent proliferation of smaller capacity turbocharged petrols. You get the reliability of petrol (less expensive kit trying to keep them clean), the economy & emissions of a small engine (for most driving) with the power of a larger engine when needed.

Unfortunately many people will be swapping one problem for another - ie DPF for turbo because most people have no idea how to "care" for a turbo and their driving style is often very mechanically unsympathetic.

Personally, I am a huge fan of turbocharging (or supercharging). I currently drive a Saab 9-3 with a 2.0 litre turbo engine tuned to 270hp with 104k on the clock. My previous car was a Rover 800 Vitesse Sport (also 2litre turbo) that went to 187k in 15 years and I sold it to an ROC member. Neither car has ever missed a beat. But then, I'm an automotive engineer and I know how to look after a turbo (and cars in general).

BMW 320D Touring - Petrol vs diesel. Small estate - Engineer Andy

Do you still really need an estate car (large amount of loads being moved around, etc), as this could limit you a bit to what you can go for. Diesel is fine if (as you say) you do a reasonable amount of out-of-town driving, but really if in addition its lugging really heavy loads around (not just people and a some stuff in the boot) and for annual mileages at least over 15k miles a year, prefereably over 20k miles.

Modern diesels don't like regular short journeys and will lead to poor (and expensive to fix) reliability problems, as they rely on lots of technology to duck under (in theory, now with the VAG scandal perhaps not in practice without possibly sacrificing performance and/or mpg) the emissions regulations, which appear not to work well/be susceptible to issues when driven in this way.

The politicians are now just waking up to this and are considering new rules/laws on NOx & particulate emissions relating to vehicles, whether demanding all new ones meet the limits in more real-world driving (not just in the lab or via 'cheat' technology) and also instituting 'low emissions zones' in cities (like London) where they may ban certain vehicles from driving in them if they don't meet the new regs.

As such (this seems to be a theme at the moment), stick with petrol cars, and again, if you tend to keep your car a long time (well over 5 years), then Japanese (and maybe Korean) is the way to go, as they are more likely to be problem-free in later life and tend to be less complex/cheaper to look after than some of the European makes, some of whom (e.g. VAG) still appear to be suffering from above average reliability issues across their ranges (not just diesel-related issues).

I would read through the 'Car by Car' reviews in HJ's Reviews section - look at as many makes/models as might satisfy your needs (including past models, lower down on each make's list of models), paying particular attention to the 'Good and Bad' parts. Some (like my car - Mazda3) have most of their 'Bad' entries related to diesel issues (they share them with Fords using the same shared engines on some models), and don't assume that one entry means all such cars have that issue (the VAG DSG clutch issue crops up time and again, which tends to mean it is a common issue).

BTW - what budget are you looking at (assuming you'll get maybe a Grand or so for your current car at best)? Also to factor in insurance (far higher on German/premium [perceived quality - normally more about 'plushness' and performance/handling than actual engineering quality] cars than others due to the high list price and of parts/fitting costs) and running costs (servicing, fuel, VED, replacement parts [clutch, tyres, etc]) over your likely ownership period as a whole. For long onwership periods, depreciation matters nowhere near as much as if you only keep it for less than 5 years, hence why so many people buy Japanese cars for long-term buys.