Diesel vs petrol

Gentlemen, we are dealing with a question from the fairer sex here, when it comes to that showroom moment it'll all come down to "Shall I have the red or yellow one?"

(I'm joking, but still, time to flee! :exit:)
 
My wife drives a 50mpg petrol car, I'll give you it's a small engined one (700cc with a turbo), tax is cheap, insurance is quite cheap too. Her car - a Smart Roadster, 2 seater mid engined convertible that gets lots of looks wherever it goes, and corners very well. The boot is a bit of a joke though. Oh and she absolutely loves it and won't part with it until it either dies or we leave the country!
 
I swapped my Nissan 200 SX 2 litre turbo petrol for a Kia Cee'd 1.6 CRDi in February this year and I'm delighted with the new car. Acceleration is down and getting a real wheel drift on is not going to happen, but in every other way the car is better.

Fuel economy is up from 30 mpg to 60 mpg, saving around £800 per annum.

Road tax is down from £225 to £0 due to low emissions.

A season ticket for the local country parks is down from £65 to £0 due to low emissions.

Insurance is down from £250 to £200.

I now have a 7 year warranty ahead of me and a fixed price service plan of £609 to cover the first five years and no MOTs to worry about for three of those.

I've gained so many gadgets and conveniences that it's hard to believe the new car cost £4,500 less than the old one did 13 years ago. I now also have a nice hatchback boot (bigger than a Focus) which saves having the dog take up the back seat and being five door instead of two it also means I can actually get the doors open wider than a narrow crack in the supermarket, and that's great for my belly.

Now the equivalent petrol Cee'd might very well have delivered some of those savings and benefits, but certainly not all of them, and my preference is for diesel grunt over revvy petrol power for road use. Of course I have started the depreciation cycle all over again, but that would be true whether diesel or petrol. Since I expect to keep the car for ten years or so the annual depreciation cost is hardly a concern in any case.
 
Last edited:
tdodd said:
my preference is for diesel grunt over revvy petrol power for road use
Click to expand...

Power delivery is a personal preference thing. As a comparison, I have two "road" cars, one petrol and one diesel.

The petrol car has a 3.2 litre naturally aspirated engine and delivers power smoothly from idle at 650rpm to the rev limiter at 7300rpm. I can pootle round in 6th at 30mph (1100rpm) and accelerate cleanly to as fast as the law allows. I can also go from 30mph to 70mph in 2nd if I prefer and get there a lot faster, of course.

The diesel has a 2.5 Turbo V6, it's the VW/Audi engine from a decade or so back. It won't do much of anything below 1900rpm and runs out of puff at about 4100rpm. There is a tremendous amount of torque in that range, but to make it go you are rowing the gearbox all the time.

I find the petrol engine characteristics more pleasant and less effort for journeys where there are a lot of speed changes, although the car itself is a good deal more "urgent" and responsive (suspension, steering etc) than the diesel, which itself is perfect for mile after mile of motorway at a constant 70mph.
 
Russ77 said:
Having only driven petrol cars, I managed to put unleaded in my diesel focus :bang:

Luckily I realised this after only 8 litres. The tank was nearly empty so I brimmed it with diesel and kept topping it up as soon as I'd used 1/4 tank.

It seems that no harm was done and I've heard of people in cold contries *having* to put a small amount of unleaded in the tank of diesels to stop the diesel 'waxing'.

Major damage can be done if you fill a diesel with unleaded and drive away from the pump. The fuel itself acts as a lubicant for the diesel pump and unleaded can cause the pump to sieze.
Click to expand...

3yrs ago I filled my car (56 litres) with unleaded and about a gallon of diesel left in the tank and in the system (you'd think all BP pumps would have each fuel in the same order but no, that and at the time they'd rather I applied for an American Express card than actually confirm on the back of the pump gun what fuel I was putting in). I drove home about a mile and a half and parked up until the next morning when the car refused to start.
I realised what had happened, had the tank drained and refuelled with diesel. Fuel pump is still working fine over 40k miles later. With the engine unable to work on petrol, it will likely stop before any real damage can be done, unless you keep trying to get he car started, forcing more petrol through the pump.
 
onomatopoeia said:
Power delivery is a personal preference thing. As a comparison, I have two "road" cars, one petrol and one diesel.

The petrol car has a 3.2 litre naturally aspirated engine and delivers power smoothly from idle at 650rpm to the rev limiter at 7300rpm. I can pootle round in 6th at 30mph (1100rpm) and accelerate cleanly to as fast as the law allows. I can also go from 30mph to 70mph in 2nd if I prefer and get there a lot faster, of course.

The diesel has a 2.5 Turbo V6, it's the VW/Audi engine from a decade or so back. It won't do much of anything below 1900rpm and runs out of puff at about 4100rpm. There is a tremendous amount of torque in that range, but to make it go you are rowing the gearbox all the time.

I find the petrol engine characteristics more pleasant and less effort for journeys where there are a lot of speed changes, although the car itself is a good deal more "urgent" and responsive (suspension, steering etc) than the diesel, which itself is perfect for mile after mile of motorway at a constant 70mph.
Click to expand...

That seems to be the opposite of my experience, I think because you have larger engines.

Petrol (1.8 and 2.0) requires lots of changing up and down, down to 2nd for round abouts, then to 3rd or 4th to stop the engine screaming.

Diesel (1.9 and 2.0) lets me leave it in 3rd and I can go from 15mph to 80mph without changing gear. The diesel will power from very early down to around 4k revs and I have pulled away in 5th (some slipping of clutch required ;) ).


Cruising in a diesel at motorway speeds is much more pleasant in the diesel, revs are around 1500rpm compared to the 3000rpm in the petrol car, if you go above 70mph, it gets worse and the petrol seems to be screaming at 4000rpm while the diesel is just getting to 2000rpm.
 
onomatopoeia said:
Power delivery is a personal preference thing. As a comparison, I have two "road" cars, one petrol and one diesel.

The petrol car has a 3.2 litre naturally aspirated engine and delivers power smoothly from idle at 650rpm to the rev limiter at 7300rpm. I can pootle round in 6th at 30mph (1100rpm) and accelerate cleanly to as fast as the law allows. I can also go from 30mph to 70mph in 2nd if I prefer and get there a lot faster, of course.

The diesel has a 2.5 Turbo V6, it's the VW/Audi engine from a decade or so back. It won't do much of anything below 1900rpm and runs out of puff at about 4100rpm. There is a tremendous amount of torque in that range, but to make it go you are rowing the gearbox all the time.

I find the petrol engine characteristics more pleasant and less effort for journeys where there are a lot of speed changes, although the car itself is a good deal more "urgent" and responsive (suspension, steering etc) than the diesel, which itself is perfect for mile after mile of motorway at a constant 70mph.
Click to expand...

Is the 3.2 a porsche?
 
srichards said:
Or something rough. Modern vauxhalls are quite nasty over 3000.
Click to expand...

It is a Vauxhall :)

But also previous Mazda did it.

To a petrol user it probably isn't screaming, but once you get used to a Diesel, cruising along at 4000rpm seems wrong.
 
1750 RPM ~ 80 MPH in my Diesel - 4000 would be close to 180!
 
Dale_tem said:
It is a Vauxhall :)

But also previous Mazda did it.

To a petrol user it probably isn't screaming, but once you get used to a Diesel, cruising along at 4000rpm seems wrong.
Click to expand...

Italians seem to make petrol engines you can rev the nuts off and they still sound fine ;) The alfa diesel is about the only one I could stand for any length of time.
 
srichards said:
Or something rough. Modern vauxhalls are quite nasty over 3000.
Click to expand...

My Astra from 2009 was sweet as a nut at 4000rpm and beyond so don't know where your info. is for the post?

My first diesel, bought recently, is giving a lot less MPG than the Astra but much more enjoyment!
 
Mikesphotaes said:
My Astra from 2009 was sweet as a nut at 4000rpm and beyond so don't know where your info. is for the post?

My first diesel, bought recently, is giving a lot less MPG than the Astra but much more enjoyment!
Click to expand...

Vauxhall insignia 2 litre petrol. 2011 model I think. Had it as a rental. Rough as a badger's when revved.
 
had first diesel a long while back - 5 yrs, and 1.3 Jtd mapped to 105hp and 200 torques. Would not go back to petrol unless in the position to buy exotica... my annual milege is about 12k so people suggest at tht mileage should be petrol, however i quite like the 70mpg verage which is a mix of approx 50% urban and 50% a roads / dual c way... not driven like a nun, but not thacked either....

Wife has a skoda octavia estate and in 6th at about 50mph, you can floor it, and overtake without having to change down... seriously impressed with it.
 
DorsetDude said:
Buying new or second hand?

[EDIT: Doh just seen you said a golf with high mileage so obviously second hand]

2nd hand the premium you pay for a diesel over petrol is not so noticable. I only do about 9000 a year and have had 2nd hand diesels for going on 10 years now. I swear it was when I first switched to diesel that suddenly the price of it overtook petrol and stayed there ever since.

Ive just quickly punched 12000 miles into a spreadsheet. for 12,000 miles a year with diesel at £1.41 and assuming 50 mpg fuel cost is £338 per year. For a petrol at £1.37 a litre, giving 40mpg fuel cost is £411. If the petrol gave you 45mpg still costs £365 p.a.

Add in the fact that often the car tax is lower on a similarly powered (or higher even) diesel to a petrol and more savings made there.

Until my last car, all my diesels had over 80,000 on the clock when I bought them. Didnt worry me. And never had to cough up for new injectors. Never had any DPF problems either and do fairly short commute (13 miles each way)

Because diesels often do higher mileages than petrol cars you should get a more recent edition of a car for the same price than you could a petrol. The old adage was, always go for a higher mileage newer car rather than low mileage old one.

2p
Click to expand...

somebodys got their figures wrong, its over £1500 for diesel not £338, £1.41 is per litre, a gallon costs £6.40
 
canonrebel said:
somebodys got their figures wrong, its over £1500 for diesel not £338, £1.41 is per litre, a gallon costs £6.40
Click to expand...

Ah you spotted my test, well done... :$

With the corrected figures, you're saving even more with diesel, £1536 a year for 50 mpg one, with £1658 for a 45 mpg petrol.
 
srichards said:
Italians seem to make petrol engines you can rev the nuts off and they still sound fine ;) The alfa diesel is about the only one I could stand for any length of time.
Click to expand...

I agree with you about Italian engines, all the way back to the introduction of Alfa's lovely twin cam engine in the 1950s. When I win the lottery I'm buying a Giulietta sprint veloce or sprint speciale.


I'm used to the Hillman Imp engine through many years of ownership. 75mph in top is 5000rpm and it is singing along at that speed and will do so all day, providing the cooling system is in good condition. It was safe to 8000rpm as standard from the factory before any modifications for racing, so 4000rpm to me is nothing, hence my surprise at "screaming".
 
srichards said:
Vauxhall insignia 2 litre petrol. 2011 model I think. Had it as a rental. Rough as a badger's when revved.
Click to expand...

You were lucky! When we rented an Insignia we got the 1.8 petrol and it was pathetic to say the least.
With 4 adults in the car it struggled to get up the mountain pass to the Cairngorms mountain railway - it literally stayed in 2nd gear for the whole climb.

fast forward a year, same trip but this time 4 adults, 1 child and a buggy and a Ford Galaxy 2L TDCI, we blasted up that hill.

Vauxhall should be shot for sticking a 1.8 engine in such a heavy car and SRI badges do not make it any quicker :lol:
 
You must log in or register to reply here.
Back
Top