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Petrol VS. Diesel - some fun figures
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10-16-2012, 12:13 PM | #1 |
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Petrol VS. Diesel - some fun figures
Hey!
So this topic is more of a information share, and see what others thoughts are. Before buying my car, I was endlessly going back and fourth between a 325i and a 320d. In the end the n47 timing chain failures and possible DFP issues with short journeys along with a good deal on a 325i swung it in the petrol favour. However, I keep asking myself if I made the right decision in terms of fuel cost, so put together a sheet to run some numbers. Here some figures: Advertised MPG: (Going to use these for my calculations, in the absence of what kind of figures I would achieve in a 320d) 320d: 59 325i: 39 (My actual is 31.7) Cost per litre: d: 1.429 i: 1.359 Cost per mile: d: 9p i: 13p Tax per year: d: £100 i: £195 Rough difference in purchase cost: £1500 - £2000 Given the 4p difference in cost per mile, how many miles need to be covered to make up the difference? £1750 / £0.04 = 43750 Miles So, taking into account an annual mileage of 10,000 it would take me 4 years to make up the extra cost in fuel. (provided the ratio between petrol and diesel stays the same) For each year, I also need to add on another £95 extra for tax. I guess this just confirms what everybody says about needing to do 12-15k a year or more to make back that extra initial price in a reasonable time frame. Recently I also got the itch to consider swapping my 325i for a 330d. (Plus about £5k-6k) and to make that cost back and given the 330d is not as effiecent as the 320d, would have taken 300k miles!!* ) *330d by my calculation of 49MPG, would cost just 2p less per mile. So 6000 / 0.02) |
10-16-2012, 12:26 PM | #2 |
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We've had similar threads on here comparing others cars.
The conclusion from many when comparing the 335i to the 335d, is buy the car you prefer to drive. There really isn't any cost between the two overall. |
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10-16-2012, 12:38 PM | #3 |
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Been through the same, and glad I chose the 325i.
You would also need to reduce the diesel mpg as I doubt anyone gets 59 in real life, possibly 45-50 mpg. I actually average approx 34 mpg out of my 325 |
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10-16-2012, 01:17 PM | #4 |
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I chose my D based on how it drove rather than the cost to run as I only do 8k miles per year.
But actually, that's not 100% true becuase in terms of the "performance feel" it was between the 330d and 335i, not the 330i so that's where it gets a bit complicated! The D was cheaper to buy, insure, fuel and tax compared to the 335 so despite my low milage, I didn't need to worry about making up the purchase price premium of the diesel, because it was actually cheaper to buy! As diesels get better and better the decision making process is going to be incresingly based on the drive as well as the economics I think.
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10-16-2012, 01:34 PM | #5 |
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how did you arrive at that calculation though
320D - 10k miles, 55MPG, @ fuel prices you've mentioned it would cost £1180 to run 10k miles 325i would cost £1930 to run 10k miles @ 32MPG That's £750 more per year in fuel costs plus additional road tax, you'll recoup in 2 years mate ? the residuals of a diesel is better than a petrol ? @ 10k miles a year, I still feel diesel's are better |
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10-16-2012, 01:43 PM | #6 |
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You can't take the absolute difference in purchase costs into account when you do these calculations though. When its time to sell the car, the diesel will still be worth more than the petrol, so you will recoup a lot of that cost at that stage.
And even then, you are not taking into account service costs. A 2.0 TDI will be cheaper to service than the 325i because it requires less oil, and will be covered by fixed price servicing, which the 325 wont be. In reality, your £5k-6k isn't the real number you should be using either. Presumably that number comes from trading in your car against another. Which isn't the actual difference of the two models worth. The actual difference in that case would be better made between the selling prices of the two models, as trading in you are always going to loose out, regardless of if you were to go to a petrol or diesel. The bulk of that cost can be associated with your want / need to change, and shouldn't be taken into consideration in these calculations. I did have some serious calculations to do before I bought my 335d, because my 2.0 TDI A4 was so terrible on fuel. It costs the same per mile in fuel as the 335d costs. The cost to change wasn't too bad, but that was the cost because I wanted to change. I also had to trade in a 3 month old motor for a 2 year old motor, a huge difference in miles (3500 against 17000), but better spec (slightly) in the BMW. The only real way you can determine the difference between petrol and diesel is against actual fuel consumption figures. No other calculations should really be factored in. At a push you could pop tax differences in there, but they will be minimal compared to fuel costs anyway, so not really worth even considering. |
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10-16-2012, 02:35 PM | #10 |
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Diesel is for company cars, tractors, trucks and boats. Not premium German cars, especially not e92 and e93.
I fear I may be shot down with that one ha ha
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10-16-2012, 05:00 PM | #11 | |
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Quote:
0.13 x 10,000 = £1300 0.09 x 10,000 = £900 Saving of £400. To make up the £1500 saved on purchase would therefore still take the 3~ years I calculated. Either way, my figures are not 100%, they are little more than back of an envelope calculations. I purposely left selling price out of all calculations because of the potential for variation. I did however look at how much a 325i and 320d that are 7 years old (55 plates) would be worth. Due to the massive variation in spec etc, its not entirely accurate but it really dosent look like the 320d holds it value much better than the 325i. At the very least, that £1500 - £2000 gap difference now, gets smaller with age. |
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10-16-2012, 05:15 PM | #12 |
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Fear not, the mountain of dead bodies from the last time that was mentioned will cushion your fall.
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10-16-2012, 05:58 PM | #15 |
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Allow me to aim - shoot and say bolox !!!!
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10-17-2012, 03:23 AM | #16 |
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My ultimate driving machine saves me £1300 a year in fuel over my old golf gti, i would call that a relatively large amount of cash!
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10-17-2012, 03:25 AM | #17 | |
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I thought it being a 2.0L d or 3.0 i would affect the price. I will say, the in-gear pickup of the 320d (and 120d I drove) was amazing! Can get off the line nice and quick in the 325i, but if sitting at 50 and put my foot down, not a lot happens unless I drop 2 gears. I can only imagine what a 330d would do! I really would love to get a big BMW d for the drive style. Part of my reason for putting these figures together again was in the hope that the 330d would make more sense in terms of cost. Give me some kind of justification for saving another £4-5-6k together to try pickup a LCI 330d! |
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10-17-2012, 03:39 AM | #18 | |
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Ha, indeed. The diesel boyz still refuse to accept their diesels do sound like diesels though. The almost brand new 320d i had as a courtesy car sounded like a tractor. My colleagues 325d 6 pot diesel sounds like a diesel. I think diesel owners often like to kid themselves about: A: How many MPGs they get B: How their cars are faster than petrols C: How their cars sound pretty much the same as petrols. |
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10-17-2012, 04:00 AM | #19 | |
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B: my car is faster than a golf gti, but slower than a z4 3.0 C. my car doesnt sound as nice as the z4 3.0 but does sound nicer than a golf gti especially at tick over! Its important to remember that both petrol and diesel cars have strong points and weak points. It comes down to what you need from a car. |
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10-17-2012, 04:14 AM | #20 | |
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For instance, i've found petrol owners far more realistic about the MPG figures they get, than diesel owners. *Awaits every diesel owner on E90Post saying "I DON'T GIVE A STUFF ABOUT WHAT ANYONE ELSE THINKS ABOUT MY PURCHASE!11!!!1" |
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10-17-2012, 04:46 AM | #21 |
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The 330d would be a sensible choice if you're after low running costs.
Not quite as good on fuel as the 320d but offers more power to compensate, will have even better residuals than a 320d and from what I've gathered is a lot more reliable. The petrols are cheaper to buy but will hold considerably less value, have quite a poor reliability record and drink a fair amount of fuel. They do sound nice so if that's your number one priority then I would buy a 335i. From an insurance point I did notice the 330d is the same cost to insure as the 335i which seems strange considering the petrol is more powerful and more likely to be ragged around by boy racers. I get the impression you're buying on the numbers so make sure you consider depreciation as that will be the biggest loss. |
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10-17-2012, 04:47 AM | #22 | |
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This argument has been done to death,and is arguably more dull than the seasonal winter tyre threads.
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