Engine Petrol or Diesel - an analysis of ownership costs

Pottsy · 30th July 2007, 12:18

This question has come up a few times before - which is cheaper to own? The diesel costs £1240 more to buy. But it's not as simple as that...

Step 1: Depreciation.

The basic cost of owning the car is simply the amount you lose from buying to selling. The depreciation of a diesel is always less than it's identical petrol (because it is a more desirable option to both the used buyer), but how much less? Looking at CAPs and Glasses and doing some graphical analysis and looking at other models, it seems to be about 4%. That means that if the petrol is worth 48% of the purchase price at 3 years, then the diesel is worth 52%.

On this assumption (4% better for the diesel), then you save £100 or so if you buy a diesel. If you think it's 3% then the numbers are different, and the petrol is cheaper. 0% means that you think both cars will depreciate at the same rate:

After 3 years:
4%: £40 to £150 (diesel is cheaper)
3%: -£125 to -£50 (petrol is cheaper)
2%: -£295 to -£240 (petrol is cheaper)
0%: -£645

The first number is for the lowest spec car, and the second for the highest spec. Reduce the number if you are keeping the car for less than three years.

For example: if you think the diesel depreciation is 3% better than petrol, and you have a mid-spec car, then choose -£100.

Remember your number...

Step 2: Running costs.

If you do 12,500 miles a year or more, then here is the table:

First 12,500 miles: £203
Next 12,500 miles: £161
Next 12,500 miles: £252
Next 12,500 miles: £161

For example: you plan to do 37,500 miles in the car, then add £203 + £161 + £252 = £616, meaning the diesel will be overall £616 cheaper to run in terms of fuel and servicing.

If you do less than 12,500 miles a year, then here is the table for you:

If you do 3,000 miles a year then:
Year 1: £32
Year 2: -£11
Year 3: £181
Year 4: -£11

If you do 6,000 miles a year then:
Year 1: £86
Year 2: £43
Year 3: £135
Year 4: £43

If you do 9,000 miles a year then:
Year 1: £140
Year 2: £97
Year 3: £189
Year 4: £97

For example: If you do just 6,000 miles a year and you are going to keep the car for 3 years, then £86 + £43 + £135 = £264.

Step 3: Add the two numbers together.

This will give you the saving/cost of running a diesel. A positive number is the amount the diesel is cheaper, a negative number means the petrol is cheaper.

For example: if I use my two italic examples above I have to add £616 from step 2 to -£100 from step 1, to make £516 (the diesel will overall be £516 cheaper for me to own).

Assumptions:

I used fuel prices of 96/97p, standard service charges, mpg from the economy survey, OTR prices from the current price list. Of course the validity of the result depends on many other factors - like the condition of the car when you sell, how you sell, how you drive (mpg) and so on. So this is just a like-for-like guide.

Honda100 · 30th July 2007, 14:08

Very very interesting.
I always knew that I had to do a high mileage to justify my purchase of a diesel, and you have just clarified how much.
It would be great to have this all in a spreadsheet that we can download and put our own figures in on a regular basis, but then I am a bit OCD at times.

Foggy69 · 30th July 2007, 15:37

Insurance costs for the diesel are higher due to it been in a higher group.
I think it was about £100 extra a year for me to insure a diesel over a petrol

czechplastik · 30th July 2007, 17:19

Quite interesting, should help the buyers

IWANTACIVIC · 13th December 2007, 01:54

very good well done , im glad i brought my cdti i was doing 20k miles a year and loved every minute of it and hope to in the furture .

robbo51 · 13th December 2007, 07:35

Even if I did 10 miles a year, I would still buy a diesel!!
The engine is superb, possibly the best diesel EVER produced.
Smooth, quiet, powerful and frugal. What else would you want (No offence Type R owners, but a Typr R-D would be awesome!!)
Nice statistics Pottsy BUT a waste of time as far as I'm concerned.
I will buy diesel everytime!

Koen · 13th December 2007, 07:57

Here in Belgium it's a bit different, but I did the calculations when I got mine, and the diesel was saving me €300-€700 a year, depending on how much km I would make.
Diesel fuel is cheaper here than petrol, but you have to pay an extra yearly diesel tax. So if you do the simpel math, the amount you save on fuel has to compensate for the extra tax.
Furthermore, a diesel costs more when purhasing, but resale value is also higher. But the extra resale value will not compensate the extra initial price paid when new. So you have to calculate some extra km a year for that, too.
It's my first diesel, and I would never have bought one if it wasn't a Honda 2.2 or a BMW 2.0. I was prepared to pay the extra money to drive a petrol. But I found the 1.8 a bit dissapointing. Or was the diesel just so good...
Anyway, I drive the diesel now and it's been a pleasure from day one. I am a bit lucky maybe, 'cause I didn't experience any of the problems I read about so often here. (Knock on wood!) So the diesel has proven to be the best choice, in terms of driving pleasure, and financially!

K.

30th July 2007, 12:18	#1 (permalink)
Pottsy Administrator Civinfo guru Join Date: 10th April 2006 Location: Leics Posts: 4,775 Thanks: 7 Thanked 64 Times in 33 Posts	Petrol or Diesel - an analysis of ownership costs This question has come up a few times before - which is cheaper to own? The diesel costs £1240 more to buy. But it's not as simple as that... Step 1: Depreciation. The basic cost of owning the car is simply the amount you lose from buying to selling. The depreciation of a diesel is always less than it's identical petrol (because it is a more desirable option to both the used buyer), but how much less? Looking at CAPs and Glasses and doing some graphical analysis and looking at other models, it seems to be about 4%. That means that if the petrol is worth 48% of the purchase price at 3 years, then the diesel is worth 52%. On this assumption (4% better for the diesel), then you save £100 or so if you buy a diesel. If you think it's 3% then the numbers are different, and the petrol is cheaper. 0% means that you think both cars will depreciate at the same rate: After 3 years: 4%: £40 to £150 (diesel is cheaper) 3%: -£125 to -£50 (petrol is cheaper) 2%: -£295 to -£240 (petrol is cheaper) 0%: -£645 The first number is for the lowest spec car, and the second for the highest spec. Reduce the number if you are keeping the car for less than three years. For example: if you think the diesel depreciation is 3% better than petrol, and you have a mid-spec car, then choose -£100. Remember your number... Step 2: Running costs. If you do 12,500 miles a year or more, then here is the table: First 12,500 miles: £203 Next 12,500 miles: £161 Next 12,500 miles: £252 Next 12,500 miles: £161 For example: you plan to do 37,500 miles in the car, then add £203 + £161 + £252 = £616, meaning the diesel will be overall £616 cheaper to run in terms of fuel and servicing. If you do less than 12,500 miles a year, then here is the table for you: If you do 3,000 miles a year then: Year 1: £32 Year 2: -£11 Year 3: £181 Year 4: -£11 If you do 6,000 miles a year then: Year 1: £86 Year 2: £43 Year 3: £135 Year 4: £43 If you do 9,000 miles a year then: Year 1: £140 Year 2: £97 Year 3: £189 Year 4: £97 For example: If you do just 6,000 miles a year and you are going to keep the car for 3 years, then £86 + £43 + £135 = £264. Step 3: Add the two numbers together. This will give you the saving/cost of running a diesel. A positive number is the amount the diesel is cheaper, a negative number means the petrol is cheaper. For example: if I use my two italic examples above I have to add £616 from step 2 to -£100 from step 1, to make £516 (the diesel will overall be £516 cheaper for me to own). Assumptions: I used fuel prices of 96/97p, standard service charges, mpg from the economy survey, OTR prices from the current price list. Of course the validity of the result depends on many other factors - like the condition of the car when you sell, how you sell, how you drive (mpg) and so on. So this is just a like-for-like guide.

13th December 2007, 07:35	#6 (permalink)
robbo51 Type S GT Civinfo guru Join Date: 1st July 2007 Location: Bingley, W.Yorks Posts: 2,833 Thanks: 39 Thanked 26 Times in 24 Posts	Even if I did 10 miles a year, I would still buy a diesel!! The engine is superb, possibly the best diesel EVER produced. Smooth, quiet, powerful and frugal. What else would you want (No offence Type R owners, but a Typr R-D would be awesome!!) Nice statistics Pottsy BUT a waste of time as far as I'm concerned. I will buy diesel everytime! Last edited by robbo51; 13th December 2007 at 07:39.

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This thread is about: Petrol or Diesel - an analysis of ownership costs, it's in Buying, Dealers and Servicing at the Honda Civic forum Civinfo; This question has come up a few times before - which is cheaper to own? The diesel costs £1240 more to buy. But it's not ...

30th July 2007, 14:08	#2 (permalink)
Honda100 Supporter Triangular Exhaust Join Date: 31st May 2006 Location: Stockport Posts: 237 Thanks: 0 Thanked 0 Times in 0 Posts	Very very interesting. I always knew that I had to do a high mileage to justify my purchase of a diesel, and you have just clarified how much. It would be great to have this all in a spreadsheet that we can download and put our own figures in on a regular basis, but then I am a bit OCD at times.

30th July 2007, 15:37	#3 (permalink)
Foggy69 Vivid Blue Rocks!!! Rocketship door handle Join Date: 5th December 2006 Location: Westerham Posts: 1,042 Thanks: 2 Thanked 7 Times in 6 Posts	Insurance costs for the diesel are higher due to it been in a higher group. I think it was about £100 extra a year for me to insure a diesel over a petrol

30th July 2007, 17:19	#4 (permalink)
czechplastik King of the rodeo Civinfo guru Join Date: 24th October 2006 Location: Belfast Posts: 4,499 Thanks: 0 Thanked 0 Times in 0 Posts	Quite interesting, should help the buyers

13th December 2007, 01:54	#5 (permalink)
IWANTACIVIC Supporter Magic Rear Seat Join Date: 16th September 2006 Location: LINCS UK Posts: 658 Thanks: 0 Thanked 0 Times in 0 Posts	very good well done , im glad i brought my cdti i was doing 20k miles a year and loved every minute of it and hope to in the furture .

13th December 2007, 07:57	#7 (permalink)
Koen Supporter Triangular Exhaust Join Date: 18th September 2007 Location: Belgium Posts: 238 Thanks: 0 Thanked 0 Times in 0 Posts	Here in Belgium it's a bit different, but I did the calculations when I got mine, and the diesel was saving me €300-€700 a year, depending on how much km I would make. Diesel fuel is cheaper here than petrol, but you have to pay an extra yearly diesel tax. So if you do the simpel math, the amount you save on fuel has to compensate for the extra tax. Furthermore, a diesel costs more when purhasing, but resale value is also higher. But the extra resale value will not compensate the extra initial price paid when new. So you have to calculate some extra km a year for that, too. It's my first diesel, and I would never have bought one if it wasn't a Honda 2.2 or a BMW 2.0. I was prepared to pay the extra money to drive a petrol. But I found the 1.8 a bit dissapointing. Or was the diesel just so good... Anyway, I drive the diesel now and it's been a pleasure from day one. I am a bit lucky maybe, 'cause I didn't experience any of the problems I read about so often here. (Knock on wood!) So the diesel has proven to be the best choice, in terms of driving pleasure, and financially! K.