100+ miles a day, diesel or petrol in 2019?

agrinnall

Tarambor wrote: »

The data I'm getting is from the manufacturer. Given that in every car I've had in the last 20 years I've exceeded the official figures I'm confident in using those as a milestone for comparisons.

Well your economic driving course must have been exceptionally good given that it's pretty well known that manufacturers figures are very rarely achieved, let alone exceeded, in real life driving conditions.

[Deleted User]

Electric would be good for a 100 mile commute. A used Leaf 30 or even a 40 if you can find an attractively priced one would be great.

If you can charge at work then even an old Leaf 24 will do.

You can't beat them for being cheap to run if you can charge at home.

fred990

agrinnall wrote: »

Well your economic driving course must have been exceptionally good given that it's pretty well known that manufacturers figures are very rarely achieved, let alone exceeded, in real life driving conditions.

I think they could be achieved/exceeded if the vast majority of people didn't drive like total knobs?
Anyway who needs a 'course' on such things? Needless to say BMW drivers are excluded.

-Enna

Ebe_Scrooge wrote: »

It depends. That sort of mileage is what diesels are supposed to be for, so the knee-jerk reaction is "yes, go for it".

However, there's a lot of variables. For starters, if you're already getting 45-ish mpg, that ain't half bad in the real world. What sort of a car would you anticipate buying - brand new, nearly new, quite a few years old ? Generally you'd have to be making a huge saving in fuel costs to offset the purchase price of a newer car.

Then you need to think of other ongoing costs - routine servicing, tyres, the cost of parts if repairs are needed, etc. If your existing car is generally reliable and cheap to maintain, you need to be wary of swapping to something that chews through tyres that cost £150 apiece, for instance.

Lastly, is it really worth it for just a few more months of doing that commute ? Will you be hit by congestion charges and clean air zones and stuff ?

So the short answer is - there is no short answer :-) But hopefully it'll give you some food for thought.

Thanks for you’re reply. I don’t have my old car anymore. It was a Ford Fiesta 1.0 Ecoboost.

I’m looking at a used, new car hopefully. No more than a couple years old as I don’t want to have to worry about MOT at the moment. Clean air zones are definitely something I’m more apprehensive about as well as the higher tax brackets and the slower rise in petrol/diesel.

It’s an open question, but in order to get the most out of a diesel longer term, how much would be the recommended annual mileage?

-Enna

Tarambor wrote: »

I've been looking at a new(er) car too. I get 55-60MPG on average out of my 9 year old 143,000 mile Mondeo 2 litre TDCi 140 as almost all mileage is A road/DC/motorway. Looking at the Ford Focus 1.0 125BHP Ecoboost petrol it looks like it would return the same fuel economy, possibly slightly better. Yeah its a slight downgrade in size but not by much and it still retains the same 0-60 time due to a similar power to weight ratio which is important for me as at certain times of the year I do a lot of overtaking of dawdling tourists on their way back home at 40MPH in 60 limit from a day at the seaside.

So that sorted my next thing I was looking at was the environment which muddies the waters. CO2 is responsible for global warming, NOx poisons us, particulates choke us in towns so I did some research. Diesel cars emit less CO2 than petrols on a like for like basis (remember above it was similar MPG for the petrol but only due to an engine half the size and lower BHP/torque) as they're a more lean burn engine. Diesels USED to emit much more NOx and particulates than petrols however with Euro 5 emission specs NOx became very close to petrol and particulate emissions were brought to zero - when did you see a 9/10 year old or newer diesel with black soot on the bumper around the exhaust like they used to? Euro 6 brings NOx levels from diesels almost down to parity with petrol and again, no particulate emissions. The diesels still benefit from lower CO2 output. For me diesel wins but only as long as it is Euro 6 or Euro 5 at a push.

Maintenance wise its in favour of the diesels. Petrol cambelt change intervals are sooner, they have spark plugs, leads and coil packs that need to be done. Both have EGRs that can clog up so that's a tie there.

But then there's the journey types. If you're not regularly doing long journeys 30+ miles or more at a decent lick then you're going to have issues with the DPF filter in a diesel.

I think it essentially breaks down into the following as a result:

If you live in a city or major town and the majority of journeys are urban with the odd trip out then its petrol.
If you live in the countryside or rural area or you do a lot of business travel so are regularly doing longer journeys then its diesel.

Thank you! What have you decided on, diesel or petrol?

Also, when you say regularly, is that 30+ miles week, a day etc?

Scrapit

agrinnall wrote: »

Where are you getting your Focus data from? I've been driving a Fiesta with that engine for the last 3.5 years and have never got anywhere near those figures, about the best I've had was 50MPG on a long motorway journey that had a lot of speed restrictions, in general use (which does include a lot of urban journeys) I get low 40s and sometimes it dips below 40. I'd be surprised if the real world figures for a heavier car can get close to your Mondeo's figures.

A 1.6 tdci focus would return those figures

Ebe_Scrooge

-Enna wrote: »

It’s an open question, but in order to get the most out of a diesel longer term, how much would be the recommended annual mileage?

It's not an exact science, but the generally accepted view is that you need to be doing about 20,000 miles a year or more to make a diesel economically viable. The two main costs are that a diesel costs more to buy in the first place than an equivalent petrol, also the fuel is more expensive (I don't know why, when I started driving, diesel fuel was always cheaper than petrol). So you need to do a fair few miles before the increased fuel economy begins to outweigh the extra costs.

That said, servicing for diesels is generally cheaper - they are fundamentally a much simpler engine, and don't have a lot of the electrical circuits since they don't rely on a spark plug to ignite the fuel.

But the type of journey you do is a big factor. Diesels like to be driven hard on long motorway runs. Endless pootling round town soon clogs up the DPF, which is expensive to replace.

So in a nutshell, and making a very broad generalisation, if you're doing around about 20K miles or more a year, and most of that is on motorways, dual carriage ways and fast main roads, then a diesel is still a sensible option to consider.

agrinnall

Scrapit wrote: »

A 1.6 tdci focus would return those figures

Not sure how that's relevant when the engine under discussion is a 1.0 125bhp petrol.

almillar

I think they could be achieved/exceeded if the vast majority of people didn't drive like total knobs?
Anyway who needs a 'course' on such things? Needless to say BMW drivers are excluded.

Absolutely not. I can be an extremely economical driver when I want to, but I've got no chance of getting good MPG on a city commute into work. If you're fortunate enough to have an economical journey, great, but there's a reason for urban/extra urban being quoted - they're different, no matter how you drive.

iolanthe07

That said, servicing for diesels is generally cheaper - they are fundamentally a much simpler engine,

Diesels may be fundamentally a much simpler engine, but not when you add on all the parts needed to cut down NOx. It is the filters and ancillary equipment that causes the problems with diesels, not the fundamental design. Citroen used to produce a simple diesel that would run on practically anything and was bombproof. No such thing as a simple diesel car engine these days.