Car running costs - mid-size car - diesel vs petrol.

[joshwa]

Hi,

I'm sure this has probably been talked to death... however. Lets say I want a used medium sized estate car (Ford Focus Estate sized), and want to choose between a petrol and diesel. I'd be aiming myself towards a diesel for MPG and low tax.

But then you enter the whole world of: DPF failures, EGR failures (VAG), Emissions scandals (VAG), false MPG figures (VAG etc).

So lets say I want to buy a £1500 Ford Focus diesel, I'm facing:

2006 Ford Focus 1.6 Diesel (with DPF): MPG: 58.9mpg (combined), TAX: £125* (newer models are £30/y)

2006 Ford Focus 1.6 Petrol: MPG: 42.2mpg (combined), TAX: £200

Over 10,000 miles, the petrol car would cost: £1355 in fuel.
The diesel would cost: £1043 in fuel.

So you save £312 (Fuel) and £75-£170 in tax. (every year in theory)

BUT how much more will it cost you in maintenance for:
DPF, EGR
Turbos
etc

Thoughts, comments, welcome.

[PC-LAD]

I'd personally go for the diesel. My dad has had diesel for years and my mum has had petrol till last year. Only non-reliable diesel my dad had was a Nissan with a Renault block underside blew off, after it ran away. his vextra has 160k miles on it now and just starting to burn oil. Beware that when you buy the car though that there is no dark smoke or it will fail it's mot. Anyway, diesels are great, they are nowhere as dirty as the government makes them out to be

[AETAaAS]

I've got a 2004 Vectra diesel with 110k miles on it. Mechanically, no problems with the engine, turbo, DPF or what have you.

Main problems are emissions as PC-LAD pointed out. It is easy to fail a MOT in a diesel since they brought in the visual test for exhaust, since if you rev it like a dumbass, a lot of old cars turbos will not have spun up enough to provide enough air to burn the diesel and you get smoke. Some garages do this to flog you a fuel treatment for 40-60 quid, but I'm sure some of them chuck in a £5 bottle of Redex and charge you stupid money.

DPF failures are most often seen on cars doing short journeys so the filter can't heat up to the correct temperature and regenerate. You can use fuel additives to help regeneration and burn cleaner but this is another added cost. I used Millers Oils additive in the past and that seemed fine. I'm trying Archoil now and also no complaints.

Downsides, you can smell an old diesel cars exhaust I don't know if its the way the air/fuel mixes were programmed or just the exhaust and filters weren't as good as modern cars but if you are idling in traffic or a parking lot, you will notice.

Diesels are harder to start in the cold. This isn't really a problem most of the time especially smaller engines, but you will kill your battery if you do a lot of short journeys in the winter as I know to my cost (which was two batteries in three years) because the glowplug and cranking the high compression engine takes quite a bit of power.

I would balance it on your commute/driving. If you are an occasional driver/short commute, I'd take petrol. If you are going to have good long A-road or motorway commutes regularly, then diesel.

[Ttaskmaster]

But then you enter the whole world of: DPF failures, EGR failures (VAG), Emissions scandals (VAG), false MPG figures (VAG etc).
So lets say I want to buy a £1500 Ford Focus diesel

Don't buy an Octavia. They're piles of junk that fall apart!

[Butcher]

Friend has a diesel Focus, it blew the turbo within 6 months. He got it replaced and it blew the new turbo. He ended up selling it at a loss. I wouldn't recommend them.

2006 cars probably won't have a DPF.

Diesel is currently more expensive than petrol, though that may change.

Don't forget to check the actual MPG you get as well, many cars have optimistic figures, so if you're basing your calcs on that, you might end up paying more than expected.

[kalniel]

The diesel probably cost more than the petrol when new, and likely also second hand, plus the cost of the fuel is different.

And at that age, it's likely to only be Euro 4 emissions compliant, so liable to be barred from some cities in the future or subject to additional fee.

Then there's the maintenance - which depends on the life they've lead before you.

But what about your journeys? If you're load lugging over long distances then I'd go diesel as you will appreciate the torque and the long drives will prevent the engine clogging up. If you don't carry much, or do shorter journeys then you can live with the reduced torque the cleaner running petrol will help the car last longer.

[Hoonigan]

I'd go diesel.

[smargh]

Annual mileage? Typical journey distance? Mostly motorway or urban?

[DanceswithUnix]

Honestly, if you are that on the shelf then probably get what looks like the nicest car you can find regardless of fuel type.

The petrol and diesel mpg figures are all lies, and not based on your typical journey. Maintenance cost of any old car is down to luck unless you personally know the person you are buying it from.

Old diesel cars are more complex than old petrol cars, there is more to go wrong but *if* you are doing lots of long journeys then the fuel is way cheaper. I had a diesel and did short town journeys and the fuel economy sucked.

I believe the Focus diesel has a dual mass clutch with an eye watering replacement cost, so watch for clutch slip if you go that route.

If you want low running costs, I would look at Japanese stuff.

[joshwa]

Annual mileage? Typical journey distance? Mostly motorway or urban?

Mileage between 8000 and 13000/year.

Mostly motorways (to work and back) - 28 miles a day (for work) more for other stuff.

[smargh]

For 14mi each way I'd consider just getting a very nice ebike, if the route isn't too sh***y & personal/work circumstances permit. Maybe £2-3k for a really nice one.

Consider trying one out. Halfords might still do a 24h trial.

[kalniel]

For 14mi each way I'd consider just getting a very nice ebike, if the route isn't too sh***y & personal/work circumstances permit. Maybe £2-3k for a really nice one.

Consider trying one out. Halfords might still do a 24h trial.

I don't think you can get an estate's worth of kit on a bike. Also, they're not quite motorway suitable

Given it's motorway journeys then I'd be slightly swayed in favour of diesel.

[Xlucine]

I'd say, spend that £1500 on a mkI Škoda Octavia 1.9tdi with the ASZ engine (1999-2004, roughly). Get the non-VRS model, you'll still have up to 130BHP and can remap that for an extra 40, if you like.

No DPF, as they didn't exist back then. This has a PD (Pumpe Düse) injected engine, not CR (Common Rail), so no need for a DPF to balance it.
EGR is right on the top and easily got to, removed and cleaned out yourself, no expensive mechanic's bills to worry about.
Emissions on this are generally much better than modern diesels and this is before those scandal causes were even conceived.
MPG is very good and very accurate, at least according to my Fuelio app.
Turbo is relatively easy to replace, but very easy to clean out yourself - Push some Mr Muscle oven cleaner through it once a year, job done. Yes, really.

Parts are cheap and plentiful, and it's a great drive, too.

What mileage does it give on motorways? Most of the difference in cost between the brochure figures for the focus are due to the MPG differences, so any large deviation from the MPG of the more modern diesel would bring us right back around to guesstimating the average DPF replacement cost per year (as the old diesel burns more fuel, but doesn't need DPF fixing). My 75 gets ~45 on a motorway commute of similar length (and has common rail but no DPF. EGR didn't survive the previous owner, so no soot accumulating the in the inlet manifold).

[DanceswithUnix]

No DPF, as they didn't exist back then. This has a PD (Pumpe Düse) injected engine, not CR (Common Rail), so no need for a DPF to balance it.

Emissions on this are generally much better than modern diesels and this is before those scandal causes were even conceived.

I thought the PD engines ran at a higher compression ratio, making them more prone to small particulates and NOx emissions? So a PD engine would benefit in emissions from a DPF, they just weren't mandated back then so weren't fitted.

Particulates isn't about soot, it's the really microscopic particles that get deep into your lungs, hence direct injection petrol engines now have to be fitted with them.

Mileage between 8000 and 13000/year.

Mostly motorways (to work and back) - 28 miles a day (for work) more for other stuff.

Diesel sounds like the best bet for you.

[Spud1]

Mileage between 8000 and 13000/year.

Mostly motorways (to work and back) - 28 miles a day (for work) more for other stuff.

On those sort of trips and that mileage I'd be pushing you towards petrol - the difference in fuel cost is about 8-10p/ltr between petrol & diesel (in manchester at least) which should offset any potential MPG gain, which would be very minor anyway on such short journeys.

I should say that I would push you towards petrol anyway since I typically hate the noise & feel of most diesels, particularly older ones, but that's a personal thing. I am happy to take a relatively small hit on MPG for owning a car with a nicer engine

[kalniel]

I should say that I would push you towards petrol anyway since I typically hate the noise & feel of most diesels, particularly older ones, but that's a personal thing. I am happy to take a relatively small hit on MPG for owning a car with a nicer engine

That very much depends on the diesel (and indeed, petrol) engine in question. While many diesels feel terrible, there are several more free-revving examples that feel more like driving large capacity petrol engines. And conversely, modern small highly turbo'd petrol engines can feel quite like diesels