Diesel or Petrol?

Diesel's are great.*


*Under warranty.


I wouldn't even consider owning a modern diesel outside of a warranty period. Every day I see the plight of the modern diesel owner, and it isn't pretty, injectors, high pressure pumps, dpf's...uergh.
 
Fuzz said:
I'll just leave this here. :D

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The driver seems like an idiot. I believe said something 'raped an M3'. I don't think the BMW was even trying. He on the otherhand, was driving like a challenged boy-racer. Plus I think he nearly took out some of the bikers.

Finally, he missed the straight at the end - probably the best bit for that vehicle!
 
rare said:
Diesel's are great.*


*Under warranty.


I wouldn't even consider owning a modern diesel outside of a warranty period. Every day I see the plight of the modern diesel owner, and it isn't pretty, injectors, high pressure pumps, dpf's...uergh.
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I don't think you can generalise here - brands/marques, what age are you classing as 'modern' ?
 
I think you can to be honest. Most of them a liability at some point or another.

VAG and certain French brands specifically. 1.4/1.6 HDI, might as well make the turbo a service item.

I would class anything modern as being Common rail / direct injection.
 
Well, the trends in some GM and French cars are to shrink the engine capacities and increased the forced induction, so you get the Mitsubishi Evo saga where a little engine is tuned within an inch of its life and fails due to components not able to withstand the punishment.
 
Jez said:
22-23mpg on a motorway run
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I'm surprised it's not a fair bit more than that, my reasoning is this average from my truck, running at full weight ~44t gross, the aerodynamics of a large building and the drag of six axles and a 13litre engine.
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At lighter loads, a gross of say 25 - 30t, it'll easily hit 10+mpg on a motorway cruise.

Its often struck me as surprising that something relatively "small" (by comparison to an HGV) gets such a relatively low mpg given it's a mere fraction of the size, weight / mass and engine size of my truck.

I'd either expect you to get better or the truck considerably worse.... A scientist I am not though!
 
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pepsilol said:
Yes I am! Are you ready for the punch line.......?


I don't even go off road!
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:confused: What's that go to do with anything?

The point is that you say you were brought up not to waste money, but you are discounting certain options based on minor cost differences in a vehicle which is going to be very expensive to run anyway. The phrase "penny wise, pound foolish" seems quite apt.
 
Scania said:
Its often struck me as surprising that something relatively "small" (by comparison to an HGV) gets such a relatively low mpg given it's a mere fraction of the size, weight / mass and engine size of my truck.

I'd either expect you to get better or the truck considerably worse.... A scientist I am not though!
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I suppose if you gave cars a billion gears like HGVs have they would do a lot better mpg though.
 
Scania said:
I'm surprised it's not a fair bit more than that, my reasoning is this average from my truck, running at full weight ~44t gross, the aerodynamics of a large building and the drag of six axles and a 13litre engine.

At lighter loads, a gross of say 25 - 30t, it'll easily hit 10+mpg on a motorway cruise.

Its often struck me as surprising that something relatively "small" (by comparison to an HGV) gets such a relatively low mpg given it's a mere fraction of the size, weight / mass and engine size of my truck.

I'd either expect you to get better or the truck considerably worse.... A scientist I am not though!
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For perspective what does your car get?
 
mccarf said:
I suppose if you gave cars a billion gears like HGVs have they would do a lot better mpg though.
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True, although something like a modern BMW auto has 8 forward gears, my Scania "only" has 12, not exactly billions....

Jonnycoupe said:
For perspective what does your car get?
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On a motorway run, mid to high 30's, at the same speed as the truck (55mph) probably a few more not that I do 55 on a motorway cruise generally.
 
I only have 5 gears Scania, and also a power to weight ratio of 125hp/tonne, while that is not loads its a lot lot lot more than an HGV at full load. The Range Rover will also happily do over 100mph safely and will cruise usually at 75mph :)

Onto a fair comparison;

I'd guess that if you fitted a range rover with a 25BHP (10HP/tonne) 2 cylinder diesel engine with a similar power to weight ratio to a fully loaded truck (a truck is what, 440hp and 44 tonnes so 10hp/tonne?) with a final drive giving a max cruise speed of 56mph at 1200rpm or whatever a truck does, it would get amazing MPG :)
 
I imagine your HGV's gearing and engine will be designed to be working at the most efficient engine load point at steady cruise of 56miles per hour, whereas passenger cars are far more transient (in general).
 
DaveyD said:
I imagine your HGV's gearing and engine will be designed to be working at the most efficient engine load point at steady cruise of 56miles per hour, whereas passenger cars are far more transient (in general).
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Also the main point which I edited in above, a truck has less than 10BHP/tonne at full load. Imagine fitting the Range Rover with 10HP tonne via a 2cyl TurboDiesel with 25HP total, and cap its max speed to 56mph while fitting a final drive which equates to 1200rpm or so.

A fully loaded truck would need an engine capable of a max output in the region of 5500BHP to be as "nimble" as a Range Rover V8 N/A.
 
Dogbreath said:
:confused: What's that go to do with anything?

The point is that you say you were brought up not to waste money, but you are discounting certain options based on minor cost differences in a vehicle which is going to be very expensive to run anyway. The phrase "penny wise, pound foolish" seems quite apt.
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Look after the pence and the pounds will look after themselves...
 
The is a good guide ot the pros and cons of Diesel here:


TLDR: Because Diesel and Petrol both cost around 40p you need to do 70,000 miles to recover the extra cost of buying a Diesel, and the're also really slow, and throw clouds of soot everywhere.
 
If you want a V8 Range Rover get the petrol. If you want to save money get something else entirely.
 
ubersonic said:
The is a good guide ot the pros and cons of Diesel here:


TLDR: Because Diesel and Petrol both cost around 40p you need to do 70,000 miles to recover the extra cost of buying a Diesel, and the're also really slow, and throw clouds of soot everywhere.
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I think Diesels still take a while to accrue their purchase price back if you end up owning it for the full length of the contract; on lease hire though it is negligible.

Diesels offer awesome performance though which not many people actually realise - check out the BMW 335d which can do 0-60 in 4.8secs; the 335i can only do it in 5.2secs.
 
Jez said:
I only have 5 gears Scania, and also a power to weight ratio of 125hp/tonne, while that is not loads its a lot lot lot more than an HGV at full load. The Range Rover will also happily do over 100mph safely and will cruise usually at 75mph :)

Onto a fair comparison;

I'd guess that if you fitted a range rover with a 25BHP (10HP/tonne) 2 cylinder diesel engine with a similar power to weight ratio to a fully loaded truck (a truck is what, 440hp and 44 tonnes so 10hp/tonne?) with a final drive giving a max cruise speed of 56mph at 1200rpm or whatever a truck does, it would get amazing MPG :)
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Thanks for that, well explained. :)

I would love to see the results of a project car designed as you describe, I wonder if it's been done by anybody yet? - off to Google I go!

In the mean time, I'll carry on being very non scientific! :o
 
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