Fuel Consumption (Petrol vs. Diesel)

Soldato
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I always thought Diesels would be a wise choice given any circumstance (town driving, motorways etc.) however, I've noticed on the forums that people said there isn't much difference in terms of saving. If anyone can prove this, mathematically, that would be great.

I recently had 1.4 RT Clio which I drove around town and on the motorway. On average, I got around 35 miles to the galon (300-350 miles to the tank) which isn't that impressive but still.

My dad, owning a Golf TDI can get around 600 to the tank doing mostly town driving which works out at around 45-50 miles to the galon.

I recently drove upto Lancaster from london, which is 540 miles there and back. This needed nearly 2 tanks of petrols where the TDI could do it in 1 tank...
 
How much does diesel cost over there?
Down here it costs an arm and a leg compared to petrol :eek:
 
fuel economy diesel is superior as diesel engines are about 30% more efficient than petrol. However here in the UK diesel fuel is more expensive than petrol also diesel cars generally are more expensive than their petrol counterpart too.

So whilst you save money on fuel economy when driving the diesel, there is an initial greater expensive buying a diesel car. It really depends on your driving, if you do a lot of miles then diesel will work out cheaper.

Having said that, when you sell your car on, diesels tend to command a slight premium over petrol models so despite being more expensive to purchase you should also make more money when it comes time to sell. Really depends on the type of car we're talking about though.
 
35mpg from the 1.4 is bad :( I get that from my 2 litre, although I guess it's a newer engine design.
 
triggerthat said:
I always thought Diesels would be a wise choice given any circumstance (town driving, motorways etc.) however, I've noticed on the forums that people said there isn't much difference in terms of saving. If anyone can prove this, mathematically, that would be great.

Certainly. Lets pick my favourite car of the moment for this illustration - the BMW 5 Series. We'll pick a 2001/51 plate example with 'average mileage' from a private seller for ease of calculations.

BMW 530i Sport: 29mpg combined. 01/51: £12600
BMW 530d Sport: 39mpg combined. 01/51: £14280

So, there is nearly £2000 between the two. Lets do some maths.

Assume petrol is 91.9p a litre, diesel is 94.9p a litre (Prices from my local garage).

If you do 5000 miles in a year, it would cost you £720 to fuel the 530i and £535 to fuel the 530d. So, you'd save less than 200 quid a year by choosing a diesel. Thats about 16 quid a month. ie, absolutely nothing, especially when you've just spent £10k+ on a car.

What about if you do average mileage, 10k miles a year? Well, the saving doubles to nearly £400. Wow. Staggering. 30 quid a month.

Now lets talk above average mileage... 15k miles in a year. Now its £1600 to fuel the diesel and £2160 for the petrol. But thats still only 500 quid more - even doing this sort of mileage it would still take 4 years to even BREAK EVEN on purchase price.

Now, this doesn't take into account residuals - the 530d, sure, its £2k more to buy, but when you sell it 3 years later it'll probably still be worth about a grand more than the petrol, which is fair enough. It also doesn't take into account the fact some people just PREFER diesel - the power delivery style, the effortless availability of torque. Again, this is fair enough.

But from a PURELY financial point of view, the general concencous of 'If I get a diesel, I will save money on fuel' is almost NEVER true unless you do proper high mileage. And even if you purchase a diesel for the SAME price as a petrol, with the figures above, your savings are barely worth writing home about, are they?

It's a largely psychological thing (Note to the guy who went off one last time I used this phrase and accused me of calling half the forum mentally unstabled - look this word up in a dictionary please) - you WILL fill up less with a diesel so it'll seem like you are saving loads. I found I was visiting the petrol station loads more when I got the Mondeo after the Xantia TD, but sitting down and crunching the figures and - you guess it - in the real world, the extra cost was marginal.
 
Sure I could sit down and do the maths and be happy with a petrol in theory, but the diesel keeps me smiling in practice, even if it is only a percieved advantage.

The thing I really noticed going from a petrol to a diesel was motorway journeys. It seemed you'd use twice as much petrol as diesel (as triggerthat said). For me, theres a huge comfort value in putting £25 in the tank as opposed to £50.

TDF.
 
[TW]Fox said:
Lets do some maths.
...badly :D
If you do 5000 miles in a year, it would cost you £720 to fuel the 530i and £535 to fuel the 530d.
£553 for the 530d
What about if you do average mileage, 10k miles a year? Well, the saving doubles to nearly £400.
£334
Now lets talk above average mileage... 15k miles in a year. Now its £1600 to fuel the diesel and £2160 for the petrol.
£1659 for the diesel.

Sorry, had to be done ;) :D

The one area diesels do still make very good sense is company cars, where you're not paying the initial price premium nor the (often) increased servicing costs. The tax is also lower, although nowhere near as good as it used to be due to the abolishment of the 3% discount for Eu4 engines.
 
Vertigo1 said:
The one area diesels do still make very good sense is company cars, where you're not paying the initial price premium nor the (often) increased servicing costs. The tax is also lower, although nowhere near as good as it used to be due to the abolishment of the 3% discount for Eu4 engines.

And another Area they are good at is if you decide to drive through deap water :p
 
I think the Diesel vs Petrol argument is alright for buying a new car... but for the majority of people who buy used and like to get as good a deal as possible I think the savings on diesel may be more pronounced?
 
Zip said:
How much does diesel cost over there?
Down here it costs an arm and a leg compared to petrol :eek:

I bet its still cheaper there in Oz.

About 8 years ago I picked up a girl From NZ at the airport, as we passed a fuel station she was horrified by the price of the Fuel, She was even worse when I pointed out that it was actually the price of a Litre and NOT a gallon! :p
She was saying that the Kiwis were moaning when it exceeded around 50p a gallon.
 
"What about if you do average mileage, 10k miles a year? Well, the saving doubles to nearly £400. Wow. Staggering. 30 quid a month. "

Thats almost an extra tank of diesel for me, i.e another 450-500 miles for the same money. No brainer as far as im concerned. Some diesels may cost more than SOME petrols, but sometimes there isnt an equivalent so the waters are muddied.
For the record i do about 15k a year, and im happy getting the extra miles and not having to fill up as much as i used to.
 
Rich said:
"What about if you do average mileage, 10k miles a year? Well, the saving doubles to nearly £400. Wow. Staggering. 30 quid a month. "

Thats almost an extra tank of diesel for me, i.e another 450-500 miles for the same money. No brainer as far as im concerned. Some diesels may cost more than SOME petrols, but sometimes there isnt an equivalent so the waters are muddied.
For the record i do about 15k a year, and im happy getting the extra miles and not having to fill up as much as i used to.

What about the extra initial cost etc that fox pointed out earlier in this post.

edit: im talking crap, you noticed lol :o
 
35mpg from the mk1 1.4 clio is not bad at all! That's one of the better results I've heard. Coming from a fellow owner, I'm lucky if I get 20mpg, but the tank is only 11 gallons. Not big at all. If you got 350 miles from it that's fine. ;) But diesels are better, my dad's van does ~450 - 500 on a tank. But again, it's a bigger tank. :)

EDIT: Also factor in the age now of those kind of cars and the efficiency will be degraded.
 
Im getting a golf gti diesel next because they do 52 mpg whereas the petrol do 35, this is a big saving especially as i do all my driving on the motorway so i should get better figures than the ones quoted
 
k3v said:
Im getting a golf gti diesel next because they do 52 mpg whereas the petrol do 35, this is a big saving especially as i do all my driving on the motorway so i should get better figures than the ones quoted
Yes you save just over 50% more.... which still isnt a great deal.
 
moss said:
What about the extra initial cost etc that fox pointed out earlier in this post.

edit: im talking crap, you noticed lol :o


Just to clarify, i bought a Skoda Fabia VRS. To be fair, at the time, there was nothing that came close in terms of bang for buck, not to mention residuals.
I guess what im saying is, that for some cars, maybe even most, the diesel thing doesnt work out (depending on your circumstances). But there are exceptions to that rule.

I like the way diesels drive also, i like the power delivery. I like knowing that if im making a long motorway journey i can fill her up and not have to worry about it for another 550-600 miles.... and we are talking about a 45 litre tank here.


There are more pro's to Diesel than just gas costs imho.


Its things like this :
http://forums.overclockers.co.uk/showthread.php?t=17592523

That dont do the debate any good :D
 
How can people like the way diesels drive. I drove a (1.8T?) Passat last week and it felt like it had power for about a second then felt dead.
 
Berger said:
Yes you save just over 50% more.... which still isnt a great deal.


You will have to elaborate a litle on that one! Im nost sure if you were joking or not :)
 
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