Diesel vs Petrol

[ryallm]

Just been soing some calcs on running costs of diesel vs petrol for a daily driver with interesting results. Just bought a Renault Megane Estate for my wife Helen. 1.6 petrol Dynamique, 2 1/2 yrs old, near mint condition, 20 k miles, and seems a very good buy at £5700 - given Renault's reputation for reliability, or lack of, hope I am still saying that in a years time . Anyway, the equivalent diesel would have been at least £1000 more to buy, and you would almost certainly have to accept a higher mileage car. Given that diesel is circa 10p more per litre, average mpg of 38 petrol and the 55 for the diesel, I reckon you would have to do 50k miles just to break even on the extra cost of a diesel, and that is before you even take into account shorter service intervals and sometimes suspect reliability of modern common rail diesels. Conclusion? Unless you are doing mega miles, a used diesel doesn't make financial sense for most mid sized cars. I wonder how many used buyers actually do the sums before taking the plunge? TBH I didn't, but looks like my gut feeling that petrol was the way to go was correct.

Mark

[douglasgdmw]

Mark,

Know what you mean about the sums but the way things are going with the petrol prices the resale of diesels will be a lot better than that of petrol models, was that put into your calculation at all?

Had a Megane diesel as a hire car in Italy last year, could not believe that when it was fully brimmed the computer said you could do over 950 km to a tankfull. Nearly choked when I got back to the UK !!

Cheers
DMW

[ryallm]

Mark,

Know what you mean about the sums but the way things are going with the petrol prices the resale of diesels will be a lot better than that of petrol models, was that put into your calculation at all?

No, and I am sure you are right that resale value can be a big factor. But in this case assuming the car doesn't do the traditional French thing and fall apart, we'll probably keep it a long time and run it into the ground by which time it will be worth nothing, so resale isn't quite so important.

Mark

[Rag_It]

but the way things are going with the petrol prices the resale of diesels will be a lot better than that of petrol models

I am not entirely sure i understand the above, however i am hungover, and things take time to sink in, but i am intrigued, as i am selling the Discovery TD5 and wondering whether it is worth going for a petrol as doing less than 10k miles a year, and with the 10p more a litre at the moment, i am also thinking Diesel is not the way forward.

Dave

[Corranga]

I've been having this thought for a while now...

The resale values thing is obviously a thing to be considered, but then the petrol with lower miles in the first place would obviously still have less miles, and therefore likely be in better condition by resale time too.

Interesting that people always refer to 'petrol prices' when diesel prices are also on the rise, always more than petrol, and with current trends actually going up FASTER than petrol!

[H8OAG]

Just been soing some calcs on running costs of diesel vs petrol for a daily driver with interesting results.

Agreed

I travel over 40,000 miles per annum each year and Petrol makes sense at the moment

Equivalent model in diesel would have been at least £4k more to buy and the current differential of up to 12p per litre finally nails it for me.

Large Petrol Saloons (heavy metal) are unloved in the trade so can be bought at remarkable money. (I paid £16k for a 54 plate one owner A8 4.2 LWB with 50k miles last week)

A Diesel will depreciate less than its petrol equivalent but not so much at my level of mileage

But who knows what the wonderful Mr Darling will do next that will change things once again!

[ngaff1]

I'm about to start using a 50:50 mix of veg oil in the Defender, should keep the costs down a bit

[douglasgdmw]

but the way things are going with the petrol prices the resale of diesels will be a lot better than that of petrol models

I am not entirely sure i understand the above, however i am hungover, and things take time to sink in, but i am intrigued, as i am selling the Discovery TD5 and wondering whether it is worth going for a petrol as doing less than 10k miles a year, and with the 10p more a litre at the moment, i am also thinking Diesel is not the way forward.

Dave

Dave,

No expert and just personal opinion. I would reckon that the way the goverment are going, anti petrol lobby and prices that diesels are going to have better and better residuals.

Nobody 10 years ago would have considered a family sized diesel unless they were a taxi driver, farmer or sales rep, nowadays a lot of people are choosing diesels over petrol equivalents.

Regarding your decision, go onto Parkers and get the prices for the petrol/diesel equivalents and see whether it is worth going for the petrol or the diesel based upon residuals. Alternatively find someone in the trade and have a look at the glass's guide tosee the difference.

Reminds me of my personal project I did in my final years as a Maths student - wrote a program to determine the most effective time to purchase a motor vehicle based upon Glass's residual values, expected mileage and contract hire prices using statistical analysis techniques as well. Only real project I enjoyed at University

Cheers
DMW

[Lazydonkey]

Totally agree - im current getting 51mpg easily from the panda on my 84 mile daily round trip and there is just nooooo point in chopping it for a diesel from a cost point of view

[Mr Momo]

Just bought a diesel passat estate (140bhp / 240lbft) to replace the old passat estate ( 150bhp, 150lbft) - went from a dodgy 20mpg round town/28mpg open road to 35mpg / 45mpg equivalent. Road tax also lower band and just as fast in real-world terms (~40mpg @ 85-90tuts on the m90 ).

Didn't do the maths in detail, because the petrol/diesels were "roughly" same by the time residuals etc taken into account.

I'm impressed by the mid range, but it is a bit lardy off the line - Oh, forgot - it's still running in

Oh yeh - and a 550mile range....

[campbell]

It's not all just so clear cut though.

The Mk4 Golf GTi Anniversary is a really interesting one. 180bhp petrol or 150bhp diesel. £500 to separate them in purchase price, maybe 1 sec to separate them 0-60. But 50-70 (where it matters) they are they same (in fact the diesel may be quicker) and mpg is clearly skewed in favour of the Diesel.

Lisa bought the diesel and nearly 6 years on we have never looked back. Never had a tank return less than 43mpg (and that includes some with bike racks and roofbox on) and m-way cruise consistently 50mpg. As for driveability, it's night and day against petrol. All the diesl torque is there at very low revs, so accessible in a non-offensive way.

I take what Mark says on board fully. However, not sure if a 1.6 petrol equates to a 1.9 or 2.0 diesel...you may want to look at relative performance figures to get a more accurate comparison, the recompute the numbers.

I accept that diesel fuel is getting stupidly expensive c.f. petrol. But nonetheless we are not ready to decamp back to petrol, until the technology catches up (which it might...FSI and GDI engines are coming along nicely).

Just my 2p!

Campbell

[fd]

MY A6 2.5tdi is more fuel efficient than Nikkis 1.6 petrol A3, day to day, real world driving (not figures from a book), sure if you hoof it at 100tuts on the motorway with the trailer on tow, it isn't, but in all other cases it's a clear winner . . . I do 60miles per day motorway, she does 50miles per day motorway so a reasonable comparison . . . the A3 is 9000 miles service interval, the A6 10000 miles, service costs (for me) are no different . . . even given the price differential the A6 is comparable in terms of running costs . . . but it's a much larger car . . . go figure . . . I've also driven, reasonably regularly, the same vintage 2.8 (or is it 2.6 ?) petrol V6 A6 and I'd take the diesel every time . . . and get 30% more miles per tank . . .

I have no idea how your maths works, but for me, by any measure, the diesel is the better buy . . . oh, and I also run cars for 200+K miles so resale value is not relevant . . . and I only buy second hand . . .

Fd

[ryallm]

.

I have no idea how your maths works, but for me, by any measure, the diesel is the better buy . . . oh, and I also run cars for 200+K miles so resale value is not relevant . . . and I only buy second hand . . .

Fd

The maths is dead simple - just based on a fuel cost per mile of a 1.6 petrol Megane estate vs the 1.5 diesel, with the latter typically being 1000 to 1500 more expensive for a 3 year old car. There is also a 1.9 diesel Megane but they are pretty rare (and pricey) second hand.

Seems to me from all the above comments that it is not clear cut either way, and it pays do do the sums for whatever car you are buying. Money aside, driving characteristics are definitely a factor of course, and for many cars the low down torque of a diesel is preferable for daily driving - not always though. Helen's last car was a Pug 307 2 litre HDI diesel which was a loathesome device in every way.

Also worth pointing out that there is a lot of evidence on internet forums and reliability surveys of some common rail diesels going expensively wrong with turbo and injector problems. Ford and Mazda common rail's seem to be a bit prone to this. I gather none of the VAG diesels were common rail until very recently so are relatively bombproof.

Mark

[Rich H]

LPG is still 55p a liter. Looks like a sensible option at the moment... But the conversion grants have now gone.

Anyone LPG'd an Elise? Lots of space behind the seats if you fancy sharing the cabin with a bomb...
Could it be boxed in? Or maybe drop the petrol tank and slip in a big LPG tank then fit a petrol tank above it behind the seats?

[fd]

perhaps the maths works in your example, but it doesn't work in mine . . .

Diesel figures are from my car, Petrol from a relatives, mpg are real averages over a month each, fuel costs are the forecourt cost in Perth yesterday.
A6 2.5 TDI vs A6 2.6 petrol, same age, expected ownership milage, 150K miles, both cars are 10K service interval, 80K belts interval with negligable service cost difference (the diesel may actually be cheaper in parts costs) , the diesel was at most a couple of K more than the petrol to buy, the fuel cost differential is >6K, cars are of very similar performance, 150K miles is only 5 years driving for me, last car I sold had done 300K miles.

112 diesel per litre
38 mpg
150000 miles
3947.37 gallons
17944.74 litres
20098.11 pounds

106 petrol per litre
27 mpg
150000 miles
5555.56 gallons
25255.56 litres
26770.89 pounds

Playing with the spreadsheet . . . 45K miles lifetime reduces the difference to 2K . . . less than 2 years driving for me.

So the simple conclusion is, buy a diesel and keep it . . . if you chop and change cars regularly you're getting shafted in all possible respects, many much more so than fuel costs.

$0.02

Fd

Edited to add, even at 20K for fuel it's probably 100K cheaper than using public transport . . .