VAG - Diesels are a no go in small cars

[singlespeed]

I'm not surprised new golf diesel sales are down, considering they're only available in the highline model. Alot of people don't want to pay 36K+ for a 'standard hatchback'. It's like they don't even want to push them..

They can't even keep the TSI in stock, they sell as fast as they arrive. I agree there should be a Comfortline TDI.


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[AndrewBurns]

Small modern turbo petrol engines are very close in efficiency to diesel engines now and given the relative prices of petrol and diesel and the premium you pay at purchase for the diesel version there's just no argument economically for the diesel in most cases. What's more is DPF diesels work their best after they've warmed up and need long trips to meet their fuel consumption figures and regen their DPF's. Most drivers in Australia are going to be living in cities and for stop-start city driving the petrol is a better choice from a technical point of view.

My Father is looking at medium SUV's right now and I told him to look at the petrol models for those reasons.

[tigger73]

Small modern turbo petrol engines are very close in efficiency to diesel engines now and given the relative prices of petrol and diesel and the premium you pay at purchase for the diesel version there's just no argument economically for the diesel in most cases. What's more is DPF diesels work their best after they've warmed up and need long trips to meet their fuel consumption figures and regen their DPF's. Most drivers in Australia are going to be living in cities and for stop-start city driving the petrol is a better choice from a technical point of view.

My Father is looking at medium SUV's right now and I told him to look at the petrol models for those reasons.

+1.

A lot of small cars are used for short trips to the shops and schools, etc.

Although this is not good in terms of wear and tear for any combustion engine (perhaps this is a good case for an electric car) the diesel is going to come out worse for wear with this type of usage.

However if you're like many modern consumers and update every 3 years when the warranty expires then it's not really going to make a lot of difference (other than the higher purchase price for diesel cars).

So I'd have to agree that petrol is sneaking ahead again.

[AndrewBurns]

Yeah the ideal is an electric car for 80% of trips (to/from work and the shops) and the internal combustion car for weekends/longer trips. Unfortunately widespread adoption of electric cars will require them to be available at reasonable prices and discounts on rego and insurance for them, because nobody is going to pay double rego and insurance for a car that's limited compared to a petrol.

Technically though electric car technology is already mature enough for a practical and affordable commuter/shopping trolley car, the real holdup at this point is market acceptance. It's like a chicken and egg problem.

[Transporter]

What's more is DPF diesels work their best after they've warmed up and need long trips to meet their fuel consumption figures? and regen their DPF's. Most drivers in Australia are going to be living in cities and for stop-start city driving the petrol is a better choice from a technical point of view.

My Father is looking at medium SUV's right now and I told him to look at the petrol models for those reasons.

It's a petrol engines that have a much worst fuel economy when they're warming up than the diesels. You need to drive both to compare.

My daughter has 2012 TDI Tiguan and 2 years of extremely short trips (6-7km in city traffic), didn't have any ill affect on the DPF, and the 2years average fuel consumption of 6.5L/100km. I must admit that she does two 22km trips at the end of the week as a part of her travelling, that's all what is needed these days for the latest DPF equipped cars to regenerate the DPFs.

Even the hybrids today still have the combustion engine and the short trips won't be good for it, not talking about the batteries that will have a decreased performance if you do only the short trips, because the car will be running on that small combustion engine most of the time (unless you recharge the batteries from the grid), so the engine sludge and carbon build up will be a problem, unless you take extra care (not really common these days), the water accumulation in the fuel from condensation will also have a negative impact on such a car.
Further more, anything that turns the wheels will have the gears and oil or grease in them and the short trips won't do any good to these hybrids.

[Dutch77]

Worth pointing out the differences between Australia and say Germany (as a European proxy) on pricing too:

Sydney average ULP price $1.57/litre
Sydney average diesel price $1.54/litre

Variance $0.03/litre or 2%

Germany average ULP price $2.34/litre
Germany average diesel price $2.06/litre

Variance $0.28/litre or 12%

(note: average prices from NRMA Sydney and petrol1.de Germany for example purposes only)

Either way, on a small car where as Andrew Burns pointed out above, the variance between petrol and diesel is minimal the cost effectiveness is well in favour of petrol. It's really only going to make sense where there is a significant discrepancy between economy of the petrol and the diesel - read SUV or large sedans - or the price disparity returns between the fuel types.

[Tom87]

the increased service cost of modern diesel engines prevents me from having the desire to own them out of warranty.

common rail injectors are not cheap. my last car which had an italian diesel engine but used Bosch fuel injection system had injectors worth about $500aud each at best (more from the dealer/local distribution network, up around $800 each).

[Transporter]

the increased service cost of modern diesel engines prevents me from having the desire to own them out of warranty.

However the servicing cost of VAG TDI compared to VAG TSI should be similar no platinum spark plugs and no ignition coils to fail/replace in TDI which more than compensate for slightly more expensive TDI fuel filter compared to TSI fuel filter. Actually, the TSI engine could cost you more to service.

...and as tigger73 said, if you replace your car early after the 3 years manufacturer warranty is over, the TDI could still save you money on fuel cost and on servicing.

[pologti18t]

...and as tigger73 said, if you replace your car early after the 3 years manufacturer warranty is over, the TDI could still save you money on fuel cost and on servicing.

You just have to work out if the extra $$ to buy one (2000-2500) can be offset with fuel savings.
The other point is driveability. The modern VW TSI engine are much smoother and quieter than the diesel offerings.

[AndrewBurns]

Assuming a 0.5l/100km saving for the tdi over the tsi, diesel being 0.03c/liter cheaper and a $2000 premium for the diesel version over the petrol it would take 133000km for the diesel to break even. That's probably a best case scenario for the diesel too.