What's the line for diesel / petrol?

akira181

I'm looking at replacing my current 13 plate diesel with something newer (ideally Euro6) but I'm wondering where the line is for petrol over diesel.

My daily commute is 15 miles one way, 90% motorway, and my annual mileage 10 to 12k. I typically have a ~10 mile journey consisting of 3 stops once every weekend and a couple of much longer road trips every year.

My current diesel (1.6L Ibiza) gets 50mpg to 70mpg, depending on how much I hyper-mile. Although, if I hyper-mile for a week or so, the DPF light sometimes comes on but goes away after an 80mph drive to work.

From what I gather, I'm floating around the line where diesel is preferred over petrol but was wondering if current fuel prices, ULEZ, maintenance, etc has moved that line.

I'm rarely in the city centre so ULEZ shouldn't matter too much but Euro6 would be good for when they eventually expand the zone or if a rare occasion arises. I'd be getting a second hand car so higher initial purchase price for diesel shouldn't be a big concern (I think) although the gap between diesel and petrol is a little off-putting.

What's the consensus?

TadleyBaggie

Seems to me that diesel is probably still your best option. I always had (and preferred) diesels but since retiring I just don't to the mileage to justify it. 

Grumpy_chap

akira181 said:

My daily commute is 15 miles one way, 90% motorway, and my annual mileage 10 to 12k. I typically have a ~10 mile journey consisting of 3 stops once every weekend and a couple of much longer road trips every year.

For that use profile, you could consider EV - perhaps a Leaf? 

If you decide on ICE, then I'd say that is more petrol mileage than diesel mileage.  As you've already experienced, the use profile can cause DPF issues with a diesel.

I'm not a massive fan of them personally, but a PHEV would allow you to do most of the regular commute mileage on electric and give you the certainty for those couple of road trips.

Ebe_Scrooge

I'd say you're borderline in terms of annual mileage for petrol/diesel - probably the lower end of borderline.  And with the current price difference between petrol and diesel, it's going to take a lot of miles before the better fuel economy of a diesel will pay for the higher fuel price.

I've had diesels for many years, and do like them - mind you, up until recently I was doing 25K - 30K miles a year, so it was a no-brainer.

One option to consider may be a very small petrol car for your daily commute, and think about hiring something larger for the odd occasions you do a big journey?  Not sure whether the saving in fuel would outweigh the cost of a week's hire or whatever, but it's an option that may be worth thinking about?

Herzlos

I'd be more inclined to go petrol just to avoid the DPF issues, but petrol is a lot more popular now so price is going up and choice is going down.

You're probably better just picking a car you like within budget and not worry too much about what fuel it takes.

akira181

Grumpy_chap said:

For that use profile, you could consider EV - perhaps a Leaf? 

If you decide on ICE, then I'd say that is more petrol mileage than diesel mileage.  As you've already experienced, the use profile can cause DPF issues with a diesel.

I'm not a massive fan of them personally, but a PHEV would allow you to do most of the regular commute mileage on electric and give you the certainty for those couple of road trips.

I considered an EV/PHEV but street parking means I’m not guaranteed a spot outside my house and never the same spot twice. Even if I could park outside my home, I don't think my neighbours will take kindly to an extension cable coming from the third floor. The charging infrastructure just isn’t good enough yet and honestly, I don’t see it ever being good enough for city dwellers, unless you’re rich enough to have a flat/house with private parking or a driveway in the city, in which case you probably already own a Range Rover for all your school/grocery needs.

Herzlos said:

I'd be more inclined to go petrol just to avoid the DPF issues, but petrol is a lot more popular now so price is going up and choice is going down.

You're probably better just picking a car you like within budget and not worry too much about what fuel it takes.

My DPF light comes on a couple times a year at most, seldom enough that I wouldn’t call it an issue. A short higher speed trip on the motorway clears it pretty quick but I get it’s an expensive repair if it ever blocks.

A quick cost per mile calculation and it's roughly £0.13/mile at 60mpg (£1.75/L diesel) and 49mpg (£1.45 petrol). Having only driven diesels for the last 10 years, does/can a modern petrol car regularly achieve 49mpg with normal motorway driving (not heavy footed and not hyper-miling)?

Grumpy_chap

akira181 said:

does/can a modern petrol car regularly achieve 49mpg with normal motorway driving (not heavy footed and not hyper-miling)?

I had a 2014 Auris hybrid and then a 2007 Focus petrol.  Both delivered around 43 mpg.  Mostly motorway
My wife has a 2016 Fiesta and gets 46 mpg - nearly all town driving.

49 mpg could be achievable.

Stubod

Self charging hybrid?....I get around 65mpg out of a Niro...

CoastingHatbox

I hypermile my van all the time (returning ~65-70 mpg) and I've not had any DPF issues.

I give it the occasional thrash, not so much for the DPF but so the turbo can build some pressure and blow out any soot accumulation. Which to be honest isn't doing the DPF much good, but is probably better than thrashing it all the time as many vans are.

The van is 28% more economical than the modern, heavier but more aerodynamic, Euro VI petrol car on a long motorway journey. There is a bigger difference between the two in traffic.

Adding the cost of Adblue at my approximate usage, bought at the cheapest place I can find it (Wilko), brings the ecomony difference to around ~25.5%

And diesel is about 17% dearer than petrol around these parts.

Your commute is long enough for a Diesel to warm up properly; repeated cold starts combined with short journeys are the major concern with them.

If you get one that requires AdBlue, top it up in smaller amounts regularly to stop the AdBlue mixture from crystalising in the tank and to stop the float from seizing.

YMMV.

Bigwheels1111

The ULEZ could be a problem for euro 6 diesels from 2025-26.
Euro 7 comes out in 2025, if they then change the rules for the ULEZ YOUR STUFFED.
I can’t find any info about it.

DullGreyGuy

akira181 said:
The charging infrastructure just isn’t good enough yet and honestly, I don’t see it ever being good enough for city dwellers

That really depends on your usage and area.

In our borough the council has recently put a charging point on most the lamp posts. Leveraging solar on your roof or specialist EV tariffs is much harder but getting some form of charge daily is practical for reasonable commuting distances given the current level of EV vehicles... currently there are frequently spaces available and if 1 in 5 charging points are in use I'd be surprised

Certainly not an expert of petrol -v- diesel but very surprised your mileage is close to justifying diesel. Its going back a while but those with diesel were typically doing 5+ times the mileage