Thread: Petrol VS diesel?

Dunno .. driven sensibly, I can't see why you couldn't get that kind of economy.
Of course the lay of the land will dictate the economy.

Last time I towed anything substantial was a car from south of Sydney back to Melb.
My old Rodeo 3.2 V6 dual cab.
Me and brother.
Some place near Wollongong, I remember a very steep climb north to hit the freeway, then freeway home.
Averaged ~8km/l (high 7's) on petrol .. was the week before I had it converted to LPG.
Brother had a drive from Albury. We had a quick stop, in the days pre the bypass, then hit the freeway ... at some point just after the start of the freeway south to Melb, he must have put it in 4th.
Was at about Glenrowan somewhere near the servos that I then noticed he's still in 4th.
He drove over an hour in 4th .. still got ~8km/lt.

Rover 3500SE weighs about 1500kgs or so, trailer roughly 500-750kgs .. so about 2000kgs.

~8km/lt = ~12.5l/100

Originally Posted by PhilipA

Well I have a friend who has a 2WD Mux which I recommended to him, although I didn't know at the time you could get 2Wd.
He has a 18 foot older Jayco on road which I think has a tare of about 1400Kg.
He tows at about 80-90Kmh.
He said to me that his fuel economy goes up and down and really goes up on hills.
I replied yes that is the instantaneous but what is the average?
He said 9.3 L per 100Km.

I have another friend who has a Colorado who reckons he gets in the 7s when not towing.

These are really amazing fuel economies, and I can't think of any comparable petrol car that could come within a Bull's Roar.
Regards PhilipA

Figures aside, modern diesels are frugal, I have no problem with this argument. Modern diesels are also highly tuned, complicated, and require extremely clean diesel fuel to operate. When having this debate regarding petrol v diesel I think of it like this; there's old school diesels which can run on pretty much any diesel quality fuel, there's modern diesels which are a headache waiting to happen and then there's petrol.

I work with heavy vehicles so I love a good diesel, these modern trucks run all day and allow the modern diesel emissions equipment to operate properly... most of the time. Mum and dads who drive these same modern diesels in city stop start traffic are kidding themselves if they think they're reliable compared to old school diesel engines. I can't be bothered ranting further on this particular subject.

I drive a y62 patrol, a petrol guzzling v8 is what most of you think of it as. Yes it drinks double what a modern dual cab drinks but it also has twice the HP, considerably more torque than most and far less s#it hanging of it. There is no egr, dpf, ridiculous high pressure rail system, intercooler, turbo, etc. Around town I'm doing 18-20 and on the highway 11.5-13 depending on hills, wind, vehcile load etc.

I'd put my mortgage on the fact that my NA v8 pertol is twice as relaible as a modern diesel, cheaper to service, and ultimately cheaper to run over 150,000kms. In those kms a good majority of modern diesels will either have egr, dpf, turbo, intercooler, fuel rail issues etc.... and god forbid they actually go remote and get s#it fuel.....then you don't care about liters per hundred but dollars per engine replacement!

Moral of the story, new diesels are not old school diesels and therefore petrol wins due to its simplicity!

simplicity!

Wow , you reckon that direct port injection, dual variable camshafts, cat converters, EGR and on the latest petrols PPFs are Simple? Some also have cylinder deactivation, which I think yours has.
I reckon a gutful of water would cost the same on yours as on a diesel.

But I agree for in town use a petrol is better, but it's not the fuel economy per se that I like , its the ability to go 1400-1500Km with my long range tank and a couple of jerries. It enables me to cross the Nullabor and deviate down to Esperence via the southern coast , or up to Broome without paying a kings ransom for fuel at roadhouses.

My son bought a Subaru Diesel Outback and has done a DPF because of a loose turbo hose, and then apparently another hose blocked up, I assume it may be the EGR. His "cheap" Subaru ended up being not so cheap.
I will stick with my old fashioned TD5.

Regards PhilipA

Originally Posted by PhilipA

Wow , you reckon that direct port injection, dual variable camshafts, cat converters, EGR and on the latest petrols PPFs are Simple? Some also have cylinder deactivation, which I think yours has.
I reckon a gutful of water would cost the same on yours as on a diesel.

But I agree for in town use a petrol is better, but it's not the fuel economy per se that I like , its the ability to go 1400-1500Km with my long range tank and a couple of jerries. It enables me to cross the Nullabor and deviate down to Esperence via the southern coast , or up to Broome without paying a kings ransom for fuel at roadhouses.

My son bought a Subaru Diesel Outback and has done a DPF because of a loose turbo hose, and then apparently another hose blocked up, I assume it may be the EGR. His "cheap" Subaru ended up being not so cheap.
I will stick with my old fashioned TD5.

Regards PhilipA

No cylinder deactivation, yes DIG, yes cat converters, yes VVEL. Thats it.

Y62 has been around for over 10 years and is rock solid. Early ones had timing chain issues and this was sorted post 2012. It is a very reliable motor. VVEL and DIG is miles more reliable than anything on a modern diesel. Honda has had vtec for decades now, and DIG is not exactly new tech any more. I know vtec is different to vvel but it's cam manipulation so to speak to optimise power.

My y62 prefers premium fuel but according to the manual will run on 91 if needed, engine timing retards to reduce power. Fairly confident it would be more forgiving than any modern diesel.

And yes your td5 is a simpler engine design compared to diesel engines today

Originally Posted by 1nando

.....

Moral of the story, new diesels are not old school diesels and therefore petrol wins due to its simplicity!

Philip has the right idea!

Modern petrol engines are far from simple!

You don't even need a 'gut full of water' ... an idiot tanker driver dumping diesel into the petrol tanks at the servo! .. all it takes it one, and my mate who's a tanker driver has told me stories of dumb nuts that have done it, not taken measures to counter it and lost their jobs once found out!
I can't imagine a modern direct port injected petrol system taking too kindly to a diesel mix.

Also should be noted how many klms are going to be covered during the term of ownership of the vehicle too.
years ago I used to work as a courier, doing 90-100K klms a year.
For a vehicle that covers that many klms and does 18-20 lt/100 in such usage is going to cost far more in fuel bills than an engine rebuild would cost every 5-7 years if it were a modern 'susceptible' diesel using half as much. (at todays prices)

$1.50 x 18lt/100km x 600K klm = $50K(petrol cost for 600K klms)
$1.50 x 9lt/100klm x 600K klm = $25K(modern diesel cost for 600K klms)

$25,000 buys a lot of motor rebuilding .. and you then have the motor back to new spec! .. the petrol motor OTOH is now stuck in it's 600K klms state. You either need to buy a new car again, or still spend huge $s to rebuild the petrol motor ..

Either way .. the petrol motor still doesn't make 'economical' sense.

It's not like I haven't been there .. been there for a good many years(as a courier) .. and the one and only newish car I did buy(the Rodeo) for use as a courier vehicle lost me more money in it's life than any of the $1000 bombs I used to use prior to that.
It was cheaper to buy a bomb, spend minimal $s to get it RWC, and when it failed catastrophically .. get a new bomb again.

Then take into account the normal users usage numbers. Say 20K klms /year.
They'll probably update the vehicle every 5 years.
Petrol vehicles will lose far more value(trade in, and or second hand buyer price point). The drop in value of the petrol vehicle is going to be roughly the cost of an engine rebuild compared to the retained value of the diesel vehicle.
Classic example of this is in the 4WD market. Look at prices of V8 D2's vs TD5 D2's. TD5s are a minimum of 2x the entry price(for a given condition).

Then there is the venerable and venerated 4BD1 in my 1986 County. Dead simple in-line four cylinder pushrod engine, mechanical injection. Done 450,000 k's, uses virtually no oil, starts instantly hot or cold. Pulls like a steam locomotive. 9-10 l/100k around town and with 750 kg's in the back and the camp trailer on behind uses 11-12 l/100k up the highway going to and from swap meets. No electronics, no high pressure common rail **** to fail or to service. You could drive Perth to Brisbane with no electrics as long as you drive in daylight and park overnight on a hill.

Originally Posted by AK83

Philip has the right idea!

Modern petrol engines are far from simple!

You don't even need a 'gut full of water' ... an idiot tanker driver dumping diesel into the petrol tanks at the servo! .. all it takes it one, and my mate who's a tanker driver has told me stories of dumb nuts that have done it, not taken measures to counter it and lost their jobs once found out!
I can't imagine a modern direct port injected petrol system taking too kindly to a diesel mix.

Also should be noted how many klms are going to be covered during the term of ownership of the vehicle too.
years ago I used to work as a courier, doing 90-100K klms a year.
For a vehicle that covers that many klms and does 18-20 lt/100 in such usage is going to cost far more in fuel bills than an engine rebuild would cost every 5-7 years if it were a modern 'susceptible' diesel using half as much. (at todays prices)

$1.50 x 18lt/100km x 600K klm = $50K(petrol cost for 600K klms)
$1.50 x 9lt/100klm x 600K klm = $25K(modern diesel cost for 600K klms)

$25,000 buys a lot of motor rebuilding .. and you then have the motor back to new spec! .. the petrol motor OTOH is now stuck in it's 600K klms state. You either need to buy a new car again, or still spend huge $s to rebuild the petrol motor ..

Either way .. the petrol motor still doesn't make 'economical' sense.

It's not like I haven't been there .. been there for a good many years(as a courier) .. and the one and only newish car I did buy(the Rodeo) for use as a courier vehicle lost me more money in it's life than any of the $1000 bombs I used to use prior to that.
It was cheaper to buy a bomb, spend minimal $s to get it RWC, and when it failed catastrophically .. get a new bomb again.

Then take into account the normal users usage numbers. Say 20K klms /year.
They'll probably update the vehicle every 5 years.
Petrol vehicles will lose far more value(trade in, and or second hand buyer price point). The drop in value of the petrol vehicle is going to be roughly the cost of an engine rebuild compared to the retained value of the diesel vehicle.
Classic example of this is in the 4WD market. Look at prices of V8 D2's vs TD5 D2's. TD5s are a minimum of 2x the entry price(for a given condition).

"Mum and dads who drive these same modern diesels in city stop start traffic are kidding themselves if they think they're reliable compared to old school diesel engines."

I made this comment earlier, your courier example would not represent any significant percentage of use compared to the general population who aren't couriers.

Economy is a small price to pay for reliable motoring. I get your cost analysis for a working vehicle, is what I do for a living only with trucks. The majority of modern diesels spend they're time in stop start traffic clogging up. The fuel rail pressure in a diesel is roughly 5-6 times that of a petrol, the tiniest amount of water and it's $$$$. I can add octane booster to what I suspect might be s#it fuel and have a much better chance than a modern diesel fuel rail.

Go on the ranger forum, bt50, 200 series, prado etc pages and you can read all about bad fuel and the results. Not so common in a petrol.

As for resale, not all vehicles are the same. As an example a y62 holds its value very well, and a i30 Hyundai petrol does not.

Again I love a working vehicle with a diesel engine but the op isn't referring to working vehicles. So that argument is irrelevant to the ops point.

My experience is 400,000km with two different modern diesels - used in commuting plus the occasional trip - 100% reliable, cheaper to maintain that petrols - nothing wrong with petrol engines as most are reliable too but I do not agree with your assertion that modern diesels are unreliable.

garry