Fuel Cost Calculations??

Sit · Post by **Sit** » Wed Aug 17, 2011 9:51 pm

After doing lots of reading on here and reading and re-reading the buyers guide I am after some assistance.

Lots of people doing minimal mileage suggest the initial lower purchase price of a petrol v the diesel make the petrol a cheaper proposition for some considerable time. I am after some help calculating these costings if anyone is able to help??

At the moment I think a facelift 4.4 will be a better buy than a facelift 3.0d as I can get a lower mileage example for 8-9k as oppose to the diesel which for similar mileage and spec is more 10-11k. Our journeys are mostly around the town ferrying the little one about, I cycle to work 4 days out of six and the mrs has a Nissan Cube which she tends to use.

In the last 4 months I have probably covered 1500 miles as an indication of the use it will be getting.

If someone could help me out so I can see the cost differences on paper that would be excellent.

Cheers

Si

phill · Post by **phill** » Wed Aug 17, 2011 10:07 pm

I do similar mileage to you but drive the 4.6is and the computer is saying that I get 16 miles to the gallon, don't know if this helps, shouldn't think the miles per gallon would be much different.

Phill

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andym3 · Post by **andym3** » Wed Aug 17, 2011 11:21 pm

I have a pre facelift 4.4 and I get 17.8 mpg

petert · Post by **petert** » Thu Aug 18, 2011 1:20 pm

Getting 30mpg mixed driving from 2010 35d - not much spirited driving done in Canada though!
Peter T

X5Sport · Post by **X5Sport** » Thu Aug 18, 2011 5:47 pm

Around town we get 28mpg out of our 2005 E53 and you are realistically probably looking at 8-10mpg better for the Diesel.

The break even points are now getting further apart with recent petrol cars doing better than diesel equivalents due to initial outlay figures and the cost of fuel. I saw a report recently that suggested that smaller engined petrol cars needed to do about 30,000 miles a year before the diesel option made sense. Petrol economy is now much better than it was and the use of turbocharging has brought power levels up too. Even on a 320 and 320d, the petrol model had to do more than 8,000 miles a year before the diesel made sense.

A lot may now come down to the other running costs like insurance, tyres, spares, servicing, reliability etc. Not an easy call, but I suspect for a low annual mileage user the petrol will win, even if not by much. Â£3,000 initial outlay difference between a 3.0d and a 4.4 V8 is not insignificant after all, especially when the extra two pots used to add about Â£10k to the purchase price when new over the IL6.

Sit · Post by **Sit** » Sun Aug 21, 2011 8:43 pm

It's really tough to know what to do for the best, it would appear on paper that I could fill a 3.0d up and it would last me at least a month where as if it was a V8 it could be a visit to the pumps twice??

I messaged a guy on eBay about a facelift V8 he was selling asking about his experiences and also what he gets to a tank, he was pleased with the car and reckoned he was getting 450 miles from a tank - surely that's a little optimistic??

With people reporting 15mpg around town there is a good 10 different to the 3.0d which when you add it up does make a difference. Like you say it's the other costs - go for a V8 and you rule out troublesome and costly turbo problems which if you had to do it would make the V8 much cheaper to run!

If I was able to get 20mpg around town then I think the V8 would win hands down but with figures in the teens it might have to be a diesel.

Si

JimmySpeed · Post by **JimmySpeed** » Sun Aug 21, 2011 10:05 pm

Sit, you sound just like I did when looking for an X5, and your 1500 miles in 4 months is similar to my usage too. (apx. 5k per year give or take).

If your miles were really high it would be diesel hands down, but as they're low you are at that point where its hard to know whats best. On paper, the petrol is cheaper when you factor in lower initial cost (although this is negated slightly as it will probably be worth more when you sell it too so it balances out to some extent), cheaper maintenance and the number of miles that you will do. However you know that when you are actually filling it up yourself that 15mpg is still gonna HURT, even though you have done the sums and the petrol was the cheaper option.

I went a different route altogether and went for an LPG converted 4.4i. The car was no more expensive than it should have been for being converted - bottom line is converted or not alot of people are just avoiding anything that isn't diesel, hence sellers are desperate and there are bargains to be had. LPG costs me 62p per litre instead of petrol at 134p at my local station and LPG is about 15% less efficient than petrol so if I would be getting 15mpg on petrol (which is what my OBC tells me), then I am actually getting about 12.75mpg on the LPG.

The numbers (pound for pound and mile for mile) mean that running my car on LPG is about 45% cheaper than running it on petrol. Or put another way, I would pay Â£40.61 for 100 miles on petrol, but I pay Â£22.11 for 100 miles on LPG (which is equivalent to 27mpg at petrol prices) and I do mainly inner city 'extra urban' journeys.

For me its the ultimate compromise - the car runs the same on either fuel (its switchable via a button from inside the cabin at any time), my tank is in my spare wheel well so no boot space loss, I get the full V8 experience, someone else paid the Â£1850 +VAT for the installation and I get cheap motoring. You do need to service the LPG kit once a year which costs about Â£60, however you get a Â£20 per year road tax discount.

Its worth thinking about if you have your heart set on the V8 but don't want to be squeezed on fuel...

Sit · Post by **Sit** » Mon Aug 22, 2011 7:21 am

Thanks for that informative post mobilejo, definitely food for thought!

I hadn't really looked into LPG to be honest but it sounds good, in my ignorance I assumed that it was more efficient but not so - it's just down to it being cheaper to buy in the first place. I would worry about buying one with it already fitted so might have to pick up a bargain and get it done myself.

Trying to explain to the miss us that a 4.4 V8 is likely to be a cheaper proposition than a 3.0d is tough mind!!!! Lol!!!!

Cheers

Si

JimmySpeed · Post by **JimmySpeed** » Mon Aug 22, 2011 8:29 am

I wouldn't too much about one that's been done already - with a bit of research you'll quickly know which are the good kits and installers and if you stick with these there's not much to worry about. These particular engines are relatively simple and so very easy to convert, it's rare that the conversions go wrong.

Having said that, if you buy one and then convert it after, you have a MUCH bigger range of cars to choose from and you will get a warranty on the conversionâ€¦

Neil48is · Post by **Neil48is** » Mon Aug 22, 2011 9:16 am

Thought i put my tuppence worth in. I'm running a 4.8is on LPG,the conversion was already done on my car,however the rear end setup was far from satisfactory. The tank was too small at 48l usable volume and the pipework was a mess. I have installed a larger tank (70l usable) and sorted the pipework. As said by mobilejo you really can have the best of both worlds,my car takes about Â£50 to fill and i'm seeing around 240-250 miles for that on mainly short run mileage. And you have the satisfaction of that lovely V8 noise and performance that the 3.0d just can't match. This is my second LPG'd V8,my previous being an ML55 AMG.

JimmySpeed · Post by **JimmySpeed** » Mon Aug 22, 2011 9:28 am

[quote=""Neil48is""],my car takes about Â£50 to fill and i'm seeing around 240-250 miles for that on mainly short run mileage. .[/quote]

I'm getting about 200 for the same amount of gas, but I do believe the 4.8 is more economical than the pre facelift 4.4.

Just another reason why my next car will be a 4.8 e53 when it's time to change!

JimmySpeed · Post by **JimmySpeed** » Mon Aug 22, 2011 9:32 am

Oh and Neil's point goes to show that once a conversion kit is plumbed in, the hard work is done. At any point later you can change the individual components easily such as the tank, LPG ecu, even injectors if you are mechanically minded.

There is an LPG ecu available for mine with selectable maps for power or economy by using different fueling parameters.

Sit · Post by **Sit** » Mon Aug 22, 2011 9:49 am

That's encouraging that Â£50 will see around 250 miles in a 4.8is!!!! So is Â£1850+vat about right when it comes to the cost of having LPG fitted??

Somebody once told me as well that if you convert a car to LPG you can claim some money from the government or something like that - is this correct???

It certainly seems LPG could be the answer but one questions that is obvious - why have the government left the cost of LPG alone and not hiked it like petrol and diesel?? Could this happen one day??

Si

X5Sport · Post by **X5Sport** » Mon Aug 22, 2011 11:08 am

Unfortunately the Government grant system was closed down in 2005 as it was seen as contravening some European Regulations around state aid, or something like that. These days you have to fund it all yourself

Not sure where the idea of petrol models having lower servicing costs came from though. My 3.0D has a service every 20k miles or so under the condition based servicing, and only has oil and filters at that point. I have to have the brake fluid done every two years under the time based servicing system, but then so do all the versions.

IanP · Post by **IanP** » Mon Aug 22, 2011 11:53 am

Just a thought, if you do a lot of short journeys with a gas conversion, then it takes a while for the system to change over from petrol to gas. Mine takes about a mile at this time of year, and about 2 miles in winter. Obviously if the engine is warm then the change over is quicker. And as mentioned earlier, the standards of the companies who do the fitting can vary wildly. Mine was obviously fitted by a drunk gibbon, and I am glad I didnt pay the 2 grand out to have the work done. Try and see some examples of their work before comitting yourself. I have seen some very neat professional installations.

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