A diesel on short milage?

Joe_Horner

Don't forget that the effect of a cold engine on fuel consumption is (and always has been) a lot less for diesels than people think. To a large extent the whole "cold engines are thirsty" thing is received wisdom from the days of carburettors, where those cold miles were done with the engine choked.

That was needed to make sure enough fuel reached the cylinders without condensing onto a cold inlet manifold and would typically increase the a/f ratio at the carb to around 4:1 on full choke.

That also applies with manifold injection of petrol (especially the old single point systems), although to a smaller extent, but it doesn't apply to injection into the cylinders as diesels use because the cylinder walls heat up very quickly and don't provide a condensing surface once the engine's fired.

It's not quite "urban myth" because there are still some effects - the EMU will alter things like injection timing on a cold engine 9mainly for NOx control) and frictional losses will be higher. But it's not nearly the issue it was with your old Moggie Minor or Mk 3 Escort!

That said, as others have pointed out above, on that sort of daily mileage the difference in fuel costs will take a VERY long time to pay back the purchase price of even a cheap car. You could do it in a big block V8 and only cost yourself maybe a tenner a week extra in fuel (so 2 years to recoup that £1k purchase)!

John_Jizzle

had my diesel golf for 12 years doing around 12 miles per day - never had any issue. Road tax is about 150 a year - MPG around 45mpg

misterbarlow

We sold our 1.8 petrol for a 1.6tdi and although we only do about 9-10k a year, we now save around £100pm on fuel...

bigadaj

misterbarlow wrote: »

We sold our 1.8 petrol for a 1.6tdi and although we only do about 9-10k a year, we now save around £100pm on fuel...

Do you actually soend £100 a month on fuel. Your quote suggests you might be getting paid to drive now?

JustAnotherSaver

Just reading back the replies & it seems some of you read my post whereas some of you only read the title.

FreddieFrugal wrote: »

Well there's the crap that an old diesel will be pushing out of the exhaust if that bothers you at all.

It doesn't.

4 miles to work she might as well bike.

I love these comments. Have heard this one before actually.

With the lunatics on the roads around here? I'd personally rather be in something that can withstand a knock.
Besides, when you've been up work work early doors & you're finishing at 6:30pm-7:00pm you may want to bike home but i know i most certainly wouldn't & neither does she. Also she needs to some times call in to the supermarket to pick things up.

So anyway, to cut that one real short - no bike.

Would probably be better off just getting a smaller car with a 1.2 petrol engine. Like Fiesta size.

Wants something with a bit more nip than a 1.2 Fiesta. Having driven one myself, it has no 'nip'.

onomatopoeia99 wrote: »

Should be pointed out that for that length of journey the car won't be warm for most of it which will reduce fuel efficiency a lot.

almillar wrote: »

If you're worried about MPG, you should be. The petrol car is barely getting warmed up to its proper operating temperature, and the diesel will take even longer. So whatever MPG you read for the cars, won't apply. It'll be terrible MPG no matter what car you get.

It should also be pointed out (again) that on the following cars...

Citroen AX 1.1
Citroen ZX 1.9D
Ford Escort 1.6
Ford Escort 1.8 TDDi
Vauxhall Astra 1.8 Sri
Fiat Chinkywento 1.1 Sporting
VW Polo 1.4 MK4
Vauxhall Corsa 1.2
Ford Focus 1.6 MK1
MK4 Golf GT TDI 130
MK5 VW Polo 1.4
MK5 Golf R32
MK5 Vauxhall Astra 1.6

I have taken each of these on at least a drive to my work & back. So that's 10 mile there, 10 mile back.
On each & every one of those i either came very close to the figure quoted by Parkers (such as within 1mpg), or i matched it, or even beat it.

The only car i myself haven't been able to is my wifes MK4 Golf 1.6. I can't get near it.

So nobody can quote the short miles for the Golf when it's the exact same miles for all these other cars.

foxy-stoat wrote: »

The difference between 33 mpg and 45 mpg is around 4p per mile, assuming the petrol price is the same as diesel.

So you will be saving around 50p per day if you want to change the car to "save" money on the fuel.

If you want to change the car then do so, but try not to get hung up on mpg figures for the amount of miles your doing as 33 for a petrol isnt bad at all, I was only getting 41mpg on my PD150 golf on the daily commute.

It's not 'just' about the mpg though.

FreddieFrugal

How much 'nip' do you need on a 4 mile run?

Generally I've heard 'nippy' used to describe smaller cars with engines that are sprightly enough to make town driving - junction navigation etc - easy.

Is the Golf used for longer journeys as well like holidays - or just for the commute?

bigadaj

Sounds as though it's either that car or teh model that is causing the problems with fuel consumption.

Obvious answer is to change the car, but that's a different issue to comparing petrol and diesel, getting a different petrol vehicle sounds like the obvious answer.

JustAnotherSaver

My apologies - I should've specified that the car isn't ONLY EVER used to go to work & that there are times where it is used to go other places also. Just that work is probably 90% of its use.

foxy-stoat

JustAnotherSaver wrote: »

It's not 'just' about the mpg though.

What is it about, changing your car or justifing to yourself that you NEED to change your car?

Answering your original questions, if you want a 1.9tdi Golf for short trips then I would say get one if you want one. Nothing wrong with running an older diesel engine for short trips, wether it will return you the MPG figures what parkers say it should is another disussion. My PD150 is around 40mpg at the moment, has a few boosting issues though.

I would say that a PD130 for £1000 will require you to spend some money on maintence and repairs in the first year, be it boost hoses, clutch, cambelt/water pump, vaccum hoses, a/c repairs, MAF/MAP sensor/turbo or chasing boosting issues - you may be lucky. At this level though, I would stick with your current car as the cost saving on fuel and slightly cheaper tax will be wiped out and then some with any one of theses issues.

almillar

To a large extent the whole "cold engines are thirsty" thing is received wisdom from the days of carburettors, where those cold miles were done with the engine choked.

For petrols anyway, in the days of fuel injection, this is STILL true. It's just that the car does the choke part itself. You're still running rich when you start a petrol car cold. And if your diesel car has a catalytic converter, that's not up and running till it's up to temp either.
Another side effect of short journeys is, of course, that you'll spend a lot of your time without warm air.

I have taken each of these on at least a drive to my work & back. So that's 10 mile there, 10 mile back.

10 is not 4 to 6.