Discussion
Have I worked this out right, 3 and a bit years ago I bought a diesel car for £3750, it has averaged 50 mpg over 60000 miles.
I work that out to 1200 gallons of fuel used in 3+ years. At £6 a gallon thats £7200.
If I bought a petrol equivalent it would probably do 30mpg, thats 2000 gallons at a cost of £12000.
So by buying a diesel I have saved about 800 gallons or £4800, thats more than the cost of the car.
I thought everyone said that it was negligible the savings that diesel brought, also it is still probably worth around £1500 so to me it looks like win win. Where am I going wrong, it cant be that easy, also no repairs needed and just changed the oil/filters myself.
I work that out to 1200 gallons of fuel used in 3+ years. At £6 a gallon thats £7200.
If I bought a petrol equivalent it would probably do 30mpg, thats 2000 gallons at a cost of £12000.
So by buying a diesel I have saved about 800 gallons or £4800, thats more than the cost of the car.
I thought everyone said that it was negligible the savings that diesel brought, also it is still probably worth around £1500 so to me it looks like win win. Where am I going wrong, it cant be that easy, also no repairs needed and just changed the oil/filters myself.
No I think your math is right.
The thing is you've bought a cheap second hand diesel, had no problems and done a lot of what might be motorway miles. In that case, diesel really does win out.
However, consider a new car, you'd be paying a few grand more for the diesel over the petrol because the engine and all its band-aid emissions systems cost more (this is also coming to petrols soon so diesels won't be unique here). So you've got to make that up and petrol is 10 p a liter cheaper (approx) so you've got to overcome that as well. Both by averaging an MPG sufficiently higher than the petrol car and doing some good millage. 60k in 3 years is 20 k a year which I suspect is above average. Add in that newer petrols can also be quite good on petrol as well.
For example, my civic will garner 40-42 mpg on a motorway cruise (and thats calculated by hand). If I did 60 k miles like that I'd be spending about £8.4k on fuel at todays prices. Still more than the diesel, but its not as vast a chasm as your example. Its about £1.2k more in fuel, but I suspect the diesel Civic of same spec might be more than that in extra outlay. But then, possibly it would retain some of that come sale time. Bit of balancing act, but if you do above average miles and you can reliably get high mpg then diesels do make sense.
Older diesels like the VAG 1.9 PD's which don't have some of the newer emissions systems. A big failure on a more modern diesel could easily wipe out your fuel savings.
The thing is you've bought a cheap second hand diesel, had no problems and done a lot of what might be motorway miles. In that case, diesel really does win out.
However, consider a new car, you'd be paying a few grand more for the diesel over the petrol because the engine and all its band-aid emissions systems cost more (this is also coming to petrols soon so diesels won't be unique here). So you've got to make that up and petrol is 10 p a liter cheaper (approx) so you've got to overcome that as well. Both by averaging an MPG sufficiently higher than the petrol car and doing some good millage. 60k in 3 years is 20 k a year which I suspect is above average. Add in that newer petrols can also be quite good on petrol as well.
For example, my civic will garner 40-42 mpg on a motorway cruise (and thats calculated by hand). If I did 60 k miles like that I'd be spending about £8.4k on fuel at todays prices. Still more than the diesel, but its not as vast a chasm as your example. Its about £1.2k more in fuel, but I suspect the diesel Civic of same spec might be more than that in extra outlay. But then, possibly it would retain some of that come sale time. Bit of balancing act, but if you do above average miles and you can reliably get high mpg then diesels do make sense.
Older diesels like the VAG 1.9 PD's which don't have some of the newer emissions systems. A big failure on a more modern diesel could easily wipe out your fuel savings.
OP hand your membership card on the way out pleaseGood for you, but if you've done 20k miles a year then that's more than a lot of people do, who buy diesels because they think it'll save them money. There's a lot to be said for driving diesels if you're chugging up and down the motorway network, but the commonly held assumption that diesels are a better bet appears to be getting challenged more at the low end (old dears bumbling about to the shops etc) where potentially higher repair bills and higher costs of acquisition come in...
Your calculations are way out I'm afraid. Firstly diesel is more expensive than petrol. Secondly the MPG gap isnt as big as you think it is. My Supercharged 4.2V8 Jag will do 30MPG all day long on the motorway. So I am sure your average modern family petrol car must be able to hit 40. I have a 1.4 Petrol Daweoo for running around and that does ~ 50MPG so with petrol being cheaper than diesel that would work out cheaper than your car....
Dodsy said:
Your calculations are way out I'm afraid. Firstly diesel is more expensive than petrol. Secondly the MPG gap isnt as big as you think it is. My Supercharged 4.2V8 Jag will do 30MPG all day long on the motorway. So I am sure your average modern family petrol car must be able to hit 40. I have a 1.4 Petrol Daweoo for running around and that does ~ 50MPG so with petrol being cheaper than diesel that would work out cheaper than your car....
According to autotrader the 1.6 petrol does 32.5 mpg urban and the 1.6 diesel does 50.4, also petrol is only about 30p cheaper per gallon, I make that 5% so thats £4800-5%=4560. However you would have to visit a petrol station more often which means driving out of your way more often.
t about the extra fuel costs - that's man maths at work!I have owned a few cars in both petrol and diesel guise.
E320 vs e320cdi
3.2fsi vs 3.0tdi
535d vs 335i
330d vs 330i
Have to say that over at least 12 months and 30,000 miles the diesel has never been more than 20% better mpg wise, in some cases 10%, with petrol being around 10% cheaper the cost difference is not worth worrying about.
I borrowed a 2.0tdi A3 and a 1.4tfsi A3 recently, doing the same 90 mile round trip both returned 48mpg.
The 1.4tfsi was £2000 cheaper but had the same GFV at the end so was £65 a month cheaper.
With the price difference in fuel this makes the 1.4tfsi cheaper by around £85 a month, considering I only use £135 a month in fuel this is a big chunk.
It works at around 20% cheaper overall to drive the petrol, which was a much, much nicer all round car.
Don't compare a small 4cyl manual diesel with an old fashioned 6cyl petrol, the figures will be skewed.
E320 vs e320cdi
3.2fsi vs 3.0tdi
535d vs 335i
330d vs 330i
Have to say that over at least 12 months and 30,000 miles the diesel has never been more than 20% better mpg wise, in some cases 10%, with petrol being around 10% cheaper the cost difference is not worth worrying about.
I borrowed a 2.0tdi A3 and a 1.4tfsi A3 recently, doing the same 90 mile round trip both returned 48mpg.
The 1.4tfsi was £2000 cheaper but had the same GFV at the end so was £65 a month cheaper.
With the price difference in fuel this makes the 1.4tfsi cheaper by around £85 a month, considering I only use £135 a month in fuel this is a big chunk.
It works at around 20% cheaper overall to drive the petrol, which was a much, much nicer all round car.
Don't compare a small 4cyl manual diesel with an old fashioned 6cyl petrol, the figures will be skewed.
ctdctd said:
Did you use the trip computers version of the fuel consumption?
It may not be very accurate.
My Swift Sport says average 50mpg on the computer - actual is just over 42mpg calculated over 17K miles from new.
The trip shows 50.2 at the moment, I usually get 160 miles for £20.It may not be very accurate.
My Swift Sport says average 50mpg on the computer - actual is just over 42mpg calculated over 17K miles from new.
NH1 said:
Have I worked this out right, 3 and a bit years ago I bought a diesel car for £3750, it has averaged 50 mpg over 60000 miles.
I work that out to 1200 gallons of fuel used in 3+ years. At £6 a gallon thats £7200.
If I bought a petrol equivalent it would probably do 30mpg, thats 2000 gallons at a cost of £12000.
So by buying a diesel I have saved about 800 gallons or £4800, thats more than the cost of the car.
I thought everyone said that it was negligible the savings that diesel brought, also it is still probably worth around £1500 so to me it looks like win win. Where am I going wrong, it cant be that easy, also no repairs needed and just changed the oil/filters myself.
Now for this to be genuine ManMaths, you have to twist these numbers into a complex formula which proves that it would be financially prudent to run a Monaro instead. I work that out to 1200 gallons of fuel used in 3+ years. At £6 a gallon thats £7200.
If I bought a petrol equivalent it would probably do 30mpg, thats 2000 gallons at a cost of £12000.
So by buying a diesel I have saved about 800 gallons or £4800, thats more than the cost of the car.
I thought everyone said that it was negligible the savings that diesel brought, also it is still probably worth around £1500 so to me it looks like win win. Where am I going wrong, it cant be that easy, also no repairs needed and just changed the oil/filters myself.
My man maths for the XJR was simple. Buy a diesel and thrash it around to get performance thereby reducing MPG to about 40. Then factor in various buggeration factors like DPF , fuel pumps , injector failures all of which are really expensive.
Now take the XJR, I can get 30MPG out of it (ok I get 23 as I drive like a nob quite a lot) and it needs fairly simple servicing so my man maths using no figures, just my 'I think that' process I worked out that the Jag would be cheaper.
Its not. Oh well
Now take the XJR, I can get 30MPG out of it (ok I get 23 as I drive like a nob quite a lot) and it needs fairly simple servicing so my man maths using no figures, just my 'I think that' process I worked out that the Jag would be cheaper.
Its not. Oh well
My man maths goes something like this;
If someone did 15000 miles per year in a car that did about 60mpg you'd think that was quite financially prudent, yes?
Well, I do 7500 miles per year in a car that does 32mpg, so that is about the same cost.
And I get the benefit of 230hp and a 3.0 petrol V6, in a car that only cost £5k and is simple enough for me do do most of the maintenance on
If someone did 15000 miles per year in a car that did about 60mpg you'd think that was quite financially prudent, yes?
Well, I do 7500 miles per year in a car that does 32mpg, so that is about the same cost.
And I get the benefit of 230hp and a 3.0 petrol V6, in a car that only cost £5k and is simple enough for me do do most of the maintenance on
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