Does anyone have a petrol v diesel cost calculator?

[Chrisw666]

Just sat doing some mooching at cars and have found 2 that are comparable age, spec, condition. With the diesel at £2k more and offering a claimed 10mpg more over 36,000 miles would I actually save any money by buying the one I don't really want but SWMBO does?

I know servicing and potential issue could be more expensive with the tractor but for this exercise I just want to use fuel to convince SWMBO that we don't go far enough often enough for there to be any point in a diesel.

[SuperHangOn]

http://www.fuel-economy.co.uk/calc.shtml

[Chrisw666]

Cheers.

Petrol win,

[sjg]

This:

http://www.thisismoney.co.uk/money/cars/article-16...

Then http://www.petrolprices.com/ has average pump prices.

At current prices, 35mpg petrol will cost £6298.42 to fuel for 36k miles. 45mpg diesel will cost £5116.98.

[Mazdarese]

Chrisw666 said:

Cheers.

Petrol win,

I always manage to apply some form of man maths to make petrol win.

[Chrisw666]

Mazdarese said:

I always manage to apply some form of man maths to make petrol win.

Well over what I think the car would do in 3 years the saving of around £1k wouldn't make up for the £2k extra entry fee.

I'm counting depreciation and if I did think the tractor would take a bigger hit. Regardless of torque and how well you can remap a car the only reason for a diesel is big mileage.

[johnpeat]

If you can't do the basic maths to work out what 10mpg over 36,000 miles costs, you're not going to notice the difference anyway

As a general rule of thumb, diesels make sense when you exceed 15,000 miles a year - or if you do less but they're mostly 'motorway' miles perhaps.

For a car which does the average 10-12K and which spends a lot of that around town, the diesel won't make anything like as much sense thanks to higher purchase and running costs.

There's an exception to every rule ofc. but diesel residuals are sliding thanks to plenty of scare stories about big bills at relatively low mileages so you can't even guarantee the price differential will hold-out...

I'd be particularly wary of used diesels around the 3-4 year old/40-50K miles bracket as they're the ones most likely to blown up and cost you major monies...

[Mazdarese]

Chrisw666 said:

Well over what I think the car would do in 3 years the saving of around £1k wouldn't make up for the £2k extra entry fee.

I'm counting depreciation and if I did think the tractor would take a bigger hit. Regardless of torque and how well you can remap a car the only reason for a diesel is big mileage.

I worked out that it would cost me around £2k more in fuel over 3 years to drive a 335i over a 335d. But the d was £3k more to buy.

I plumped for the i, natch.

[Chrisw666]

johnpeat said:

If you can't do the basic maths to work out what 10mpg over 36,000 miles costs, you're not going to notice the difference anyway

It's Sunday and I've been working all day so my brain is frazzled.

I did diesel when my mileage jumped from 8k to 20k a year and it made sense in a fuel way over three years, then I sold it which hurt.

[66comanche]

Mazdarese said:

Chrisw666 said:

Well over what I think the car would do in 3 years the saving of around £1k wouldn't make up for the £2k extra entry fee.

I'm counting depreciation and if I did think the tractor would take a bigger hit. Regardless of torque and how well you can remap a car the only reason for a diesel is big mileage.

I worked out that it would cost me around £2k more in fuel over 3 years to drive a 335i over a 335d. But the d was £3k more to buy.

I plumped for the i, natch.

Quite reasonable to assume that the d would have been worth £1.5k+ more after 3 years though which would make it the all round cheaper purchase (just about) using your calculations, also presume you were looking at an auto 335i and taking road tax into account?

I wonder how a 330d would compare as well as they are significantly more economical than the 335d but with 95% of the performance.

[Lippy Kid]

I've just been working this out for an auto E39 530d vs. an auto 530i. The car would be my work commute vehicle but also my sensible wheels for anything else (although I don't do much mileage a year all told). I was thinking diesel at first, but...


Journey = 20 mile round trip (not a lot I know, but not ideal for my current daily driver).

Autotrader figures:
530d - 33.2mpg combined = £3.91 per 20 mile journey
530i - 25.9mpg combined = £4.58 per 20 mile journey


Annual work commute of 210 days/year (not including holidays):
530d - 210 x £3.91 = £821.10
530i - 210 x £4.58 = £961.80

= £140.70 saving for diesel.


2001 530d, 152k, £2995.

http://www2.autotrader.co.uk/classified/advert/201...

2001 530i, 152k (coincidentally), £1690.

http://www2.autotrader.co.uk/classified/advert/201...



£1300 difference between the 2 cars' purchase price.

Petrol it is then.

[Mazdarese]

66comanche said:

Quite reasonable to assume that the d would have been worth £1.5k+ more after 3 years though which would make it the all round cheaper purchase (just about) using your calculations, also presume you were looking at an auto 335i and taking road tax into account?

I wonder how a 330d would compare as well as they are significantly more economical than the 335d but with 95% of the performance.

Yeah my calculations took into account road tax.

I decided that I definitely wanted a 335 and after driving both variants I much preferred the petrol.

Just waiting for the DVLA to sort the plate transfer!

[calibrax]

Bear in mind that if you mainly do short journeys, you will never get the advertised economy from a diesel. Not to mention possible DPF issues. Diesel only makes sense if most of your journeys are 15 mins or more.