justification for getting a diesel for a private car

Forums › Transport (cars, bikes and boats) › justification for getting a diesel for a private car

sudo

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Ultimate Geek

#205593 18-Nov-2016 23:15

I had a couple conversations with people about justifying getting a smaller diesel vs a larger petrol

Something about a min number of kms a year (I heard 25k/year) before the diesel becomes economical than a petrol.

I want to move up from my 2L Mazda 626 to something like a 2.4L Outlander or 2.2L Tucson.

This will give me a tow rating of 2T for a smaller motor than the equivalent petrol model.

I'm not a serial tower, but have relied on my brothers Holden to tow heavier loads than my 626 can handle and need to move up to the next size family car.

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#1673950 19-Nov-2016 07:24

Don't buy a diesel for economy - buy it for the torque.

Hammerer

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#1673953 19-Nov-2016 08:10

Yes, torque for towing. That's the only reason that I'd buy a diesel for a domestic passenger vehicle.

Servicing costs are normally higher. Or service less often and let the environment pick up the tab once the particulate filter is clogged.

NZ AA comparison of diesel and petrol but there are better comparisons like this one drivingtests.co.nz

sudo

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Ultimate Geek

#1674131 19-Nov-2016 12:32

Thanks for the links, thats the sort of info I am after.

ratsun81

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#1674248 19-Nov-2016 17:28

Hammerer:

Yes, torque for towing. That's the only reason that I'd buy a diesel for a domestic passenger vehicle.

Servicing costs are normally higher. Or service less often and let the environment pick up the tab once the particulate filter is clogged.

NZ AA comparison of diesel and petrol but there are better comparisons like this one drivingtests.co.nz

The info on drivingtests site is out of date by at least 2 years. Rego prices have dropped significantly.

Try this from the NZTA if you want a good comparison.

NZTA

The other thing that most people dont realise, with a diesel the difference in economy when having a heavy right foot is no-where as high as it is when you do the same in a petrol car.

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#1674269 19-Nov-2016 18:12

Agree with all the replies... We did 1300kms last week to go to a funeral. Took the diesel X5 (turbo 3ltr) and got 8.8 L/100km doing 113kph in 110 zones (western Vic and SA) and maybe a bit quicker on some google map roads that were 1 lane wide with no hope of the Vic Highway patrol. Dead straight and flat for 50k's. Was awesome!!!

If I didn't have a lead foot (and Adelaide hills) I could've got her under 8 easily.

Today went and hired a trailer and filled it with rubbish (including old car parts, heavy steel including discs etc) and didn't even notice the trailer was there except it had a of bit rattle on the ball, which I would've sorted if it was my trailer.

alasta

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#1674271 19-Nov-2016 18:18

I own a diesel Mazda3, and this weekend I have a petrol Mazda6 (140kw version) as a rental car. I much prefer the diesel because most of the time it will do whatever you want while sitting around 2,000rpm whereas with the petrol engine I am finding that I am constantly needing to drop a gear to get up hills and out of corners. With the diesel you do need to be a bit careful with sudden throttle inputs as the huge amount of low down torque will easily kick in the traction control.

As far as operating costs are concerned, I don't think there's much in it. Buy what suits your needs - I can guarantee you will regret buying a vehicle that irritates you just because it saves a few dollars a month.

Scott3

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#1674685 20-Nov-2016 20:55

The performance difference between petrol and diesel engines depends on the specific vehicle.

Generally petrol engines will have higher performance than Diesel engines, but you have to thrash the engine (run high RPM's) to get that extra power. Generally diesels have more power available in the sub 3000rpm range where most people drive, and as such can handle bigger hills or more acceleration without dropping gears. This is the extra "torque" people are talking about, and why people rave about the drivability.

A lot of bigger vehicles (i.e. Ford territory, Hyundai Santa fe, Toyota Prado, Toyota Hilux etc) offer both 4 cylinder diesel engines (cira 120 - 140kW peak) 6 cylinder petrol engines (cira 200kW peak). In the class you are talking about the petrol engines are much smaller, so will generally offer lesser performance.

I have been really impressed with the performance of diesel engines I have driven in the (late model) VW passat/Amarok, and the Hyundai iMax van. I found the performance of the diesel in a 2 year old Prado rental I drove disappointing compared to my 10 year old 1.8L petrol corolla.

In regard to towing, how heavy is the item(s) you actually want to tow? Obviously this is something you value if you have mentioned it. Many medium SUV's and large cars vehicles are rated to tow 1500kg+ braked, but if you want a 2000kg rating there are less options. Also note that many of the euro's have high tow ratings, but low ball downforce ratings.

The advantage big of diesel car's is a diesel engine is heavier than a petrol one, and more weight in a vehicle is a good thing for towing. Having the engine make a lot of power without high RPM's also makes for a more relaxed driving experience, but tow ratings are generally more to do with transmission and brake limitations than performance in modern cars.

Diesel RUC's are charged per KM in NZ, where as petrol tax is charged per liter. If you have a fuel efficient car (say suzuki swift, corolla etc), strongly incentivized by this tax policy to get the petrol engine version. If you have a very fuel thirsty car (say a Land Cruiser / Hilux / ford transit van) you are incentivised towards diesel. The likes of the Tucson & Outlander sit near the break even point taxwise (when not towing). If you are going to do a heap of towing (enough that the fuel cost is significant) you are incentivised tax wise towards diesel (double petrol use means double tax, not so with diesel)

As other's have said, expect fuel useage to increase by more on a petrol car than a diesel car when you hook up a big trailer. This change is even more dramatic with a smaller turbo petrol engine. (they are really inefficient when you run them at high RPM)

One big advantage of Diesel cars is they typically have a much longer range on a tank of fuel.

Downsides of modern diesel cars:

Higher capital cost
Higher Rego cost
Generally higher maintenance costs

Also note that modern diesel aren't like diesels of old in regard to reliability. Out of warranty repair costs can be expected to be much higher than with a petrol engine. Consumer & regulators demand for more powerful, more refined, and less smoke belching diesels has added a lot of complexity to the engines. Things like Urea exhaust treatment add to running costs.

Read up on DPF (diesel particulate filters). In short many modern diesels have one to clean the (less harmfull, large size) particulates (soot/smoke) out of the exhaust. They are self cleaning, but need a decent (15min+) run at open road / motorway speeds in order to clean the filter. If typically drive on lower speed urban roads or in traffic, your DPF can get clogged and fail, requiring replacement.

Diesel fumes are also a known carcinogen, and have a very negitive effect on urban air quality. Europe has cottoned on to this (talk of banning diesel cars in paris etc) and realised it's pro diesel policies were a mistake. (Essentially they traded less CO2 for more urban air quality issues, and associated health effects. With hindsight a poor trade).

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#1675256 21-Nov-2016 22:26

Scott3:

Read up on DPF (diesel particulate filters). In short many modern diesels have one to clean the (less harmfull, large size) particulates (soot/smoke) out of the exhaust. They are self cleaning, but need a decent (15min+) run at open road / motorway speeds in order to clean the filter. If typically drive on lower speed urban roads or in traffic, your DPF can get clogged and fail, requiring replacement.

Diesel fumes are also a known carcinogen, and have a very negitive effect on urban air quality. Europe has cottoned on to this (talk of banning diesel cars in paris etc) and realised it's pro diesel policies were a mistake. (Essentially they traded less CO2 for more urban air quality issues, and associated health effects. With hindsight a poor trade).

This is referenced in the Auckland Unitary Plan. Schools and child care centres aren't allowed to be located within 150m of a motorway or 60m of a major road......because particulates from petrol and diesel exhaust damages the lungs of young children.

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#1675264 21-Nov-2016 23:24

Having just sold my 2012 Ranger, I recently used the cost of ownership ratings on www.carjam.co.nz to compare running costs of a near new 6 litre V8 Holden SS-V Redline ute versus a current model Ford Ranger Wildtrak. I was surprised by the results.

Factoring in the claimed fuel usage and cost over 14,000km/year, RUC (or lack of it in the Holden's case), differing rego costs, as well as differing servicing costs, I was quite surprised to learn that the 6 litre V8 Holden was only a few hundred dollars a year more to run - around a dollar a day. On paper anyway....

I briefly considered how fun it might be to have a stonking great V8 ute, until I considered a few downsides:

Firstly, as has been alluded to in other posts, a heavy foot in a petrol vehicle hits you in the wallet a lot harder than it does in a diesel - a V8 even more so

Secondly, I have a reasonably large boat as well as a 6 metre caravan. In my old Ranger, the additional fuel used to tow these was pretty minimal. This is mostly because I usually only tow them at higher speeds on open road, so I take a hit on the highway economy as opposed to urban economy (ie towing on the open road uses only slightly more fuel than not towing anything in the city) - so it almost balances out. I imagine the fuel use in a V8 would skyrocket towing these sorts of toys, and I pictured myself cringing every time I would have to plant boot to get up a hill with a load under tow.

Combine my fuel use revelations with the fact that the Holden ute is less practical (seating only 2, no 4x4 option, around half the towing capacity), and my decision is fairly obvious. A new (or near new) Ranger it will be despite the window price premium.

I rationalise my extravagance by riding a 50cc scooter to work when the weather allows for the past 7 years. I save heaps on fuel/RUC, run up lower kms on the car (less frequent servicing) and park free at the door of my work. It's probably the best $1000 I ever spent!

sudo

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Ultimate Geek

#1675283 22-Nov-2016 02:16

Towing has been an issue for me, and now I found my brother is leaving his job and his intention to get a Camry Hybrid (with a 300kg tow rating).

So now I need to do factor in cars that can tow 2T (braked) as I am also considering a caravan.

Diesel seems to be a more attractive option. I just need to get an idea of annual maintenance costs.

(even though I consider myself environmentally aware, unless I get a plug-in hybrid I don't think there is much difference between the pollutants between a modern diesel and petrol car)

pbgben

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#1675339 22-Nov-2016 08:37

My opinions differ in the environmental aspect. I love the feeling you get when a powerful diesel accelerates, the sound of the engine and turbo give me goosebumps. I usually buy on sound and looks as apposed to fuel economy but I have yet to take my life seriously yet.

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#1675356 22-Nov-2016 08:57

Scott3:

Read up on DPF (diesel particulate filters). In short many modern diesels have one to clean the (less harmfull, large size) particulates (soot/smoke) out of the exhaust. They are self cleaning, but need a decent (15min+) run at open road / motorway speeds in order to clean the filter. If typically drive on lower speed urban roads or in traffic, your DPF can get clogged and fail, requiring replacement.

Don't under-estimate how frustrating the flow-on effects of DPFs can be, going by my experience with my current car which is a diesel Mazda6. An attempt by the car to burn off the particulate can happen any time anywhere, and as mentioned above one needs to be travelling at 80km/h or higher for it to function. Given most of my driving is within city limits, I find myself needing to take drives out into the countryside solely for the purpose of letting the particulate burn-off process do its thing (this, in turn, does have a clear impact on the car's efficiency - not something I bet the official figures take into account!). I'm not willing to risk the chance of failure, which I understand did occur quite commonly with the same engine in early CX5s where people weren't always ensuring the burn-off completed.

Despite it being a great engine, given I don't tow that often and the additional maintenance costs of a diesel (next service is the first I'll have to pay for, now it's out of its three year free servicing period!) next car I buy will not be a diesel.

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#1675360 22-Nov-2016 09:12

Unless you tow I wouldn't go diesel in a small vehicle.

You pay the same road user charges ($62/1,000km) for anything up to 3,500 KG. This kills the economy of a small diesel.

If you do tow diesel is great. Fuel economy deteriorates much slower with increased load than it does in a petrol vehicle.

Mike

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Ultimate Geek

#1675363 22-Nov-2016 09:17

The turbo is something I would like to avoid ... too many bolt-ons end up becoming expensive servicing bills in the future

(especially as I like to keep my vehicle for a long time ... 10 years min)

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#1675364 22-Nov-2016 09:20

sudo:

The turbo is something I would like to avoid ... too many bolt-ons end up becoming expensive servicing bills in the future

(especially as I like to keep my vehicle for a long time ... 10 years min)

Is there such a thing as a modern diesel car without a turbo? I thought part of the very reason why diesels are now competitive with petrol-powered cars in terms of acceleration etc was the inclusion of turbos...

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