Interesting Edmunds article on new DIESELS!

Very interesting. Thanks for posting.

Some thoughts about diesel vs gas vehicles.

The price per gallon of diesel fuel is higher than the price per gallon of Premium gas in California. However, the rated miles per gallon of diesels are higher than those of gas powered vehicles.

During the energy crisis in the seventies, I bought a Volvo diesel SW GT. It was powered by a VW engine awfully under powered. Kept if for twenty years but I remember driving to Tahoe on I50 and wishing that I had purchased the gas model! Fortunately, most of our driving was in town carrying the kids to school, practice, etc. You get my drift.

Considering that the initial purchase price of a diesel vehicle is higher than that of the equivalent gas model, and that the diesel fuel is more expensive that gas, is it really worth the switch from gas to diesels?

Also Servicing needs to be considered, which is usually more expensive on diesel than a petrol (gas) vehicle.

A large well known accountancy firm in the UK did a comparison for the BBC program Top Gear, this must have been nearly 5 years ago so may need an update, but it gave interesting results.

They compared two identical vehicle by the same manufacturer a Vauxhall Vectra one a turbo diesel the other a petrol, identical price and specification except the engine.

Considering all factors, of purchase, servicing, running depreciation etc they drew the following conclusion:-

You need to be driving in excess of 40,000 miles a year to make the diesel cheaper. Anything under that the petrol car cost less money, and 5 years ago diesel was less expensive than petrol. I'd like to see the results of a similar exercise now.

Also a comment on the original article, I'd like to find anyone that constantly averages anywhere near 30mpg in a 3 litre BMW with normal daily driving patterns. These are notional figures and quite often nonsense.

Alan M.

was powered by a VW engine awfully under powered.

that I had purchased the gas model!

We had a Volvo GL with a diesel VW six (?) cylinder engine, that thing would go up the hill/mountain we lived on at 80mph, not bad for that tank

cp

"They compared two identical vehicle by the same manufacturer a Vauxhall Vectra one a turbo diesel the other a petrol, identical price and specification except the engine.

Considering all factors, of purchase, servicing, running depreciation etc they drew the following conclusion:-

You need to be driving in excess of 40,000 miles a year to make the diesel cheaper. Anything under that the petrol car cost less money, and 5 years ago diesel was less expensive than petrol. I'd like to see the results of a

similar exercise now. "

That's pretty hard to believe. The cars cost the same and the diesel should be getting much better gas mileage. Are they saying that is offset by increased cost of maintenance on a diesel? I've been maintaining a 300SD diesel for 25 years now and I'd say the maintenance cost has been either the same or less than gasoline engines I've owned. And if the diesel has higher maintenance costs, then it's strange that at 40K miles and above it comes out ahead, as most maintenance costs are mileage related as well.

was powered by a VW engine awfully under powered.

that I had purchased the gas model!

go up the hill/mountain we lived on at 80mph, not bad

Goodness gracious, cp. I correct myself re the Volvo model id. It was a GL not a GT. Makes me wonder what was wrong with the engine in our station wagon... It was maintained and serviced by the dealer during the warranty period and later on by a Volvo only shop. Go figure. We still kept it for 20 years until the day 'the tank' was finally towed away.

Hernando

The article is out of date and the engines are out of date. Huge performance, economy and refinment gains have been made for diesels in the last five years. It also depends on the manufacturers pricing policy. Many diesel cars are now no more expensive than petrol models. Diesel fuel has also increased in price compared to petrol since that report, which is a negative point.

At the end of the day, I choose diesel because I drive mainly SUV's and the advantage of diesel for these is very clear cut. I also run cars and these are also diesel but not so much for economy reasons but for the covenience of filling from my own bulk tank.

Of course there is the highly topical point about CO2 emmissions. Size for size vehicles with diesel engines use about 25% less fuel and near enough that much less CO2 is emmitted. So regardless of cost you do your little bit for the global environment by using diesel whether you downsize your car or not.

Out of interest you may like to know that my big Land Cruiser does 24 mpgUK. The Range Rover with just as much performance does 30mpg [its that new fangled common rail technology that does it] and my new little Fiat Panda consistently achieves between 60 and 70 mpg and goes like shit off a shovel. If anything the 1300cc 70hp Panda multijet engine [the very latest technology and soon to be fitted with variable vane turbos for even more power and torque] is more refined than the BMW fitted to the Range Rover.

Both the SUV's come cheaper to buy with diesel engines than petrol while the little Polish built Panda is slightly more expensive but is the most powerful, by far the torquiest and fastest version available. Imagine if everyone in America bought latest technology diesel and downsized just a bit, how much Arab oil and CO2 emmissions would be saved.

Huw

Oh yes, I forgot. Modern diesels need less regular maintenance than petrol engined vehicles in the same car range. For instance, Lets stick to the Vauxhall [a GM/Opel subsiduary for those the other side of the lake] where the latest variable service intervals allow up to 30,000 miles between oil changes for diesel engines but only 20,000 miles for the petrol versions. That is another huge saving compared with American practice of ["cheap insurance"] 3000 to 5000 mile oil changes. Even compared to 5000 miles, a modern Vauxhall or VW/Audi group diesel which is changed at every 25000 miles [for the sake of simple math] is serviced only a fifth as often. The oil is about two to three times the price of standard oil but that hardly matters if five times the labour is also saved.

And before anyone brings it up, yes the engines last as long or longer than ever before and such intervals are well proven in Europe over many years and with many brands.

Huw

And a bloody awful, dirty, unrefined, gutless, thirsty and unreliable engine that was compared to todays models. They were renouned for the overhead cams breaking and ruining the engine.

Huw

M-B is sure confident that these CDI diesels can be sold here and no doubt they'll do a good marketing job.

Higher initial cost plus higher fuel cost (due to sulfur removal and in Calif.,road taxes) and urea additive cost vs. about 1/3 improved fuel economy are valid points.

Another consideration will be the high complexity of these new diesels vs. the tough old dogs we're used to maintaining. These motors have many contemporary gas engine controls - intake air metering, EGR, electronic fuel injection plus ceramic particle traps and NOx catalysts. Technical wonders but nothing that a DIY owner can do except change the oil - the rest is too complicated.

In 1980 M-B's claim about the 300SD was that diesels had better economy (vs. the detuned gas engines of that era) and "eliminated conventional tune-ups" - true, but they "forgot?" to tell us about diesels' more frequent oil changes and the needed valve adjustments - all these maintenance costs wiped out the "savings" of a couple of dimes per gallon of fuel.

IMHO, M-B's 3.5L 24 valve, gas V-6 is the preferable power unit for anyone but very high mileage drivers.

I am sure have seen a UK break-even point of c. 20 000 less than five years ago.

I would have thought driving patterns also play a role. Don't diesels come into their own (fuel economy) in city-type driving?

DAS

For direct contact replace nospam with schmetterling

No doubt. Some cars probably need more than that. Other cars which do not claim a premium for the diesel engine start winning from the first mile. Choose carefully.

I live in the country but yes, there are bigger gains for diesel in towns. Latest technology diesels using clean fuel fuel are also acceptable from soot and other emission points of view. They don't smell and they don't burn as much fuel.

Huw

Car magazine did a test of a hybrid petrol/electric Mclass with a diesel Mclass running across the USA. There was not a great deal in it but the diesel won in economy and running cost. This was only a couple or three months ago.

Yes, very similar complex technology and hardware to a petrol engine version but much simpler than a petrol/electric hybrid. FWIW the previous Mercedes diesel engines [the four, five and straight six CDi] have not got the best reliability record in the industry, but then neither have the rest of the car.

These days the diesel goes for 15000 miles between oil changes and this is likely to increase soon, possibly to double or 30,000 miles or 2 years. They have already got the oil specification finalised for this service life and other brands already run well established 30,000 mile oil change intervals, which obviously needs ultra low sulphur fuel to be possible.

It surely depends on the driving experience and the economics where you are. You do not know any of this yet so I cannot see how you form an objective opinion. You have an opinion, yes, but not an objective one based on economics and experience of the product. When the diesel cars are available where you are, you may well find that your initial opinion is correct, or maybe not.

Huw

Yes I agree it is out of date, and I did point that out in the original post, but it was certainly an eye opener, and the 40,000 mile figure at the time was correct, the main factor back then was the petrol had 20,000 mile service intervals and the diesel was 8,000 mile, that alone wiped out a huge amount of savings.

I have both a petrol and a diesel vehicle, they are both 150 hp and both automatic, the in-gear acceleration of the diesel is far superior to the petrol, the petrol is far superior in every other respect. In comfort, noise and general running.

My diesel is a Mercedes my Petrol is a small Jaguar, both new, the jaguar hasn't missed a beat in just under a year, the Mercedes has been in for numerous problems some of which cannot actually be solved as they've never come across them before, oh and at 9 months old the entire front suspension required replacing (all under warranty of course) because it had collapsed due to component failure. But that's a different thread.

My next vehicle will probably be a diesel because of the running costs and the tax advantages as a I run business. It's likely to be an Audi, I like the look of the 3.0 TDi A4 Avant, I can then get reasonable performance with an automatic, I just don't want to drive a manual now, I see no point living on the outskirts of London.

I still don't think the difference between petrol and diesel is as big as some people suggest, but it's certainly opening up. 5 years ago I wouldn't consider a diesel, now I'd have no problem buying one, the refinement has increased that much.

ALan Mu

So costs are lower with diesel for you as they are for me. Substantially so in my case because the vehicles are so heavy.

It's likely to be

I like automatics as well and I know that the 3.0 is a monster of an engine. If anything it is too powerful big and torquey for the little A4. It will need to be a quattro to handle that torque.

Some really are as refined or more refined on the go as petrol engines. Choose carefully though because I have a Fiat Panda which is very refined and quiet but the same engine in a Suzuki Swift is quite noisy. Similarly the 3.0 BMW engine was very quiet in the X5 but is quite unrefined and noisy when pushed in my current Range Rover. Both have more engine noise than the cheap-as-chips Panda.

Huw

Yes, the GT was the 4cyl turbo, love those things.

Perhaps nothing but ours was an '84 sedan and 5spd, that makes a huge difference.

later on by a Volvo only shop. Go figure. We still

They're definitely tanks alright, I think the basic b21 4cyl engines weigh more than some compact Japanese cars.

cp

the detuned gas engines of that era) and "eliminated

more frequent oil changes and the needed valve

of dimes per gallon of fuel.

For a typical driver that would be 4 oil changes per year, a 15 minute job that costs $20 in materials and a yearly (I was told every 20K KM) valve adjustment, doesn't seem too bad to me.

cp

Which car engine manufacturer has the best reliability record?

cp

Good question. On the whole I would have to say Toyota. Nissan also have fairly bomb proof engines. Also Honda if driven fairly hard from new.

None are 100% reliable. Top three appear to be Japanese.

Individual engines designs within a brand might differ or vary in reliability.

Huw