Diesel or petrol better for loads of short journeys?
Discussion
Now there’s the trouble when you put in a truly descriptive title which the search engine can stand a chance of finding – it asks the question, so what do I say here! Someone I know makes loads of very short journeys, like 1-2 miles, and hardly any longer stuff at all.
My Spidey Sense tells me that a diesel will be more economical for this, but even Spidey can be wrong... anybody know for definite any technical reason why this would (or wouldn’t) be the case?
My Spidey Sense tells me that a diesel will be more economical for this, but even Spidey can be wrong... anybody know for definite any technical reason why this would (or wouldn’t) be the case?
Edited by Hogweed on Monday 15th June 15:52
i would argue that a modern petrol engine is more suited to lots of short journeys. In my experience diesel engines that dont get very long drives and especially ones driven short distances by grannies tend to get very clogged up and need for example replacement MAF sensors, EGR valves, glow plugs which outweigh the small mpg gain they may offer.
dave
dave
XitUp said:
Depending on how much you're wanting to spend on the car a hybrid would probably be best for this.
Surely not as it would constantly run on the petrol engine as ot would be charging up the batteries. Basically you'd be carrying loads of weight around (batteries) for no benefit.I'd go for a very small petrol engined car in these circs.
Tyre_Tread said:
XitUp said:
Depending on how much you're wanting to spend on the car a hybrid would probably be best for this.
Surely not as it would constantly run on the petrol engine as ot would be charging up the batteries. Basically you'd be carrying loads of weight around (batteries) for no benefit.I'd go for a very small petrol engined car in these circs.
If you don't have any stuff or people to carry a bike would be the best option.
Diesels may be more economical around town but if you are doing a lot of short <30 or 40mph journeys this is bad combination. You are much more likely to develop DPF and EGR problems. The engine / exhaust temperatures are extremely unlikely to get hot enough to burn off the soot which can play havoc with injectors, fuel pumps and indeed those valves for nox gas and particles.
Top it off, at 2 miles the engine isn't even warm, more fuel is injected to generate the same power form increased friction etc.
Top it off, at 2 miles the engine isn't even warm, more fuel is injected to generate the same power form increased friction etc.
My 530d is rotten at short journeys like that - it needs closer to 15 miles in winter to hit full operating temperature, and it's economy is noticeably retarded if the engine/gearbox isn't full warmed through. Even in the summer, doing lots of short town journeys means it's struggling to break 30MPG.
A small petrol sounds a much better choice to me - they warm up significantly more quickly, so their real economy ought to be better. Plus, they're much nicer full stop than a cold diesel engine, IMHO.
A small petrol sounds a much better choice to me - they warm up significantly more quickly, so their real economy ought to be better. Plus, they're much nicer full stop than a cold diesel engine, IMHO.
The key here is getting the engine up to full temperature quickly. Cold engines overfuel initially until they're all warmed up. Diesels tend to stay cold longer than petrols, mainly because of the iron engine block, and aren't as nice when cold due to piston slap (iron block/ally pistons). A small petrol engine will get hot quicker so will be more efficient.
Also as mentioned TD's need a good run every now and again to prevent the EGR getting gunked up/clear all the soot out of the turbo etc. Petrol engines don't suffer in this way to the same extent - although a trip to the red line every now and again is always a good move.
I suggest 1.1/1.0 engined micra/KA/106 etc.
Also as mentioned TD's need a good run every now and again to prevent the EGR getting gunked up/clear all the soot out of the turbo etc. Petrol engines don't suffer in this way to the same extent - although a trip to the red line every now and again is always a good move.
I suggest 1.1/1.0 engined micra/KA/106 etc.
shalmaneser said:
The key here is getting the engine up to full temperature quickly. Cold engines overfuel initially until they're all warmed up. Diesels tend to stay cold longer than petrols, mainly because of the iron engine block, and aren't as nice when cold due to piston slap (iron block/ally pistons). A small petrol engine will get hot quicker so will be more efficient.
Also as mentioned TD's need a good run every now and again to prevent the EGR getting gunked up/clear all the soot out of the turbo etc. Petrol engines don't suffer in this way to the same extent - although a trip to the red line every now and again is always a good move.
I suggest 1.1/1.0 engined micra/KA/106 etc.
Not all diesels have cast iron blocks but, even so, small petrol engine will warm up faster and is much more suited to that sort of duty...........even those with cast iron blocks, (most of them?).Also as mentioned TD's need a good run every now and again to prevent the EGR getting gunked up/clear all the soot out of the turbo etc. Petrol engines don't suffer in this way to the same extent - although a trip to the red line every now and again is always a good move.
I suggest 1.1/1.0 engined micra/KA/106 etc.
Skodaku said:
shalmaneser said:
The key here is getting the engine up to full temperature quickly. Cold engines overfuel initially until they're all warmed up. Diesels tend to stay cold longer than petrols, mainly because of the iron engine block, and aren't as nice when cold due to piston slap (iron block/ally pistons). A small petrol engine will get hot quicker so will be more efficient.
Also as mentioned TD's need a good run every now and again to prevent the EGR getting gunked up/clear all the soot out of the turbo etc. Petrol engines don't suffer in this way to the same extent - although a trip to the red line every now and again is always a good move.
I suggest 1.1/1.0 engined micra/KA/106 etc.
Not all diesels have cast iron blocks but, even so, small petrol engine will warm up faster and is much more suited to that sort of duty...........even those with cast iron blocks, (most of them?).Also as mentioned TD's need a good run every now and again to prevent the EGR getting gunked up/clear all the soot out of the turbo etc. Petrol engines don't suffer in this way to the same extent - although a trip to the red line every now and again is always a good move.
I suggest 1.1/1.0 engined micra/KA/106 etc.
MrTrilby said:
My 530d is rotten at short journeys like that - it needs closer to 15 miles in winter to hit full operating temperature, and it's economy is noticeably retarded if the engine/gearbox isn't full warmed through. Even in the summer, doing lots of short town journeys means it's struggling to break 30MPG.
A small petrol sounds a much better choice to me - they warm up significantly more quickly, so their real economy ought to be better. Plus, they're much nicer full stop than a cold diesel engine, IMHO.
My E39 528 struggles to make 20 mpg on the way to Tesco in the winter.A small petrol sounds a much better choice to me - they warm up significantly more quickly, so their real economy ought to be better. Plus, they're much nicer full stop than a cold diesel engine, IMHO.
Fatboy said:
Heh heh, brilliant. As it's for my ex wife, you couldn't be more spot on.Thanks all for your input.
Funny - my old M3 seems to return 24mpg no matter whether I drive it like it has putty con-rods, or thrash it... about 5mpg when cold.
[quote=MrTrilby]My 530d is rotten at short journeys like that - it needs closer to 15 miles in winter to hit full operating temperature, and it's economy is noticeably retarded if the engine/gearbox isn't full warmed through. Even in the summer, doing lots of short town journeys means it's struggling to break 30MPG.
My 530d doesnt take that long to warm up, 2-5 miles even in the cold
My 530d doesnt take that long to warm up, 2-5 miles even in the cold
coley20 said:
MrTrilby said:
My 530d is rotten at short journeys like that - it needs closer to 15 miles in winter to hit full operating temperature, and it's economy is noticeably retarded if the engine/gearbox isn't full warmed through. Even in the summer, doing lots of short town journeys means it's struggling to break 30MPG.
My 530d doesnt take that long to warm up, 2-5 miles even in the cold
Are you basing that solely on what the water temperature shows? If you are, I think it's misleading. It takes a lot longer for all parts of an engine - including the oil - to reach full operating temperature, as opposed to just the cooling water system.My 530d doesnt take that long to warm up, 2-5 miles even in the cold
Best wishes all,
Dave.
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