Well that all makes interesting reading.
I'm a diesel lover who has only just gone back to a petrol with my current T5 so I sit directly on top of the fence when it comes to Pertol or Diesel. Although my car is petrol the other half has a diesel. Petrol at the pump is cheaper to buy but then to be fair to most diesels you will get further in a diesel to the same amount of fuel.
I like and enjoy both types, i service them both and I insure them both.
Modern diesels are very good and as has been said they have great low down torque which gives good low down grunt which is good for everyday driving. Petrols have their upside too though and can offer vast money saving over a diesel throughout a vehicles lifetime IMHO.
If you bought 2 exact same brand new cars one petrol and one diesel and only drove 8 to 10,000 a year the petrol would be far more economical than the diesel in terms of cost, then if you up the mileage to 20,000 a year then the diesel will win hands down on overall costs.
To be fair in a comparison then you have to pick a Turbo Petrol against a Turbo Diesel just as you would have to pick a normal aspirated petrol against a normal aspirated diesel. In this instance you would get just as good get up and go from the petrol as you would the diesel with the added ability of revving higher thus needing less gear changes and ultimately providing less wear on the engine and gearbox.
Before I go on I have no idea about Volvo statistics wether or not more diesels made did or did not have the DPFs or DPFs with EOLYS or lifetime DPF's or infact had no DPF at all.
Petrols are very simple with not a great deal to go wrong and no great extras
Air, Oil, Fuel, pollen then every few years spark plugs
Extras - Brake fluid, clutch fluid, power steering fluid and coolant
Diesels for a normal service
Air, Oil, Fuel, Pollen and every few years glow plugs
Extras - Brake fluid, clutch fluid, power steering fluid, coolant, EOLYS fluid, DPF or DPF and EOLYS
So in general servicing terms the diesel is likely to cost about the same UNLESS it is indeed fitted with a DPF and especially ones fitted with DPF and EOLYS tank.
Now when you look at common problems over the life of a diesel compared to a petrol then for me it looks like this:
Turbo - both cars got one and it can fail on either with both expecting at least around 150,000 miles to a turbo (LPT Turbos expecting a little more life). If petrol is fitted with a LPT trubo then expect the that to last longer so in cost calculations will cost less overall.
Fuel Pump - You expect to last the life of a car but unfortunately most don't! If a diesel fuel pump fails then you are looking at a world of pain in the fact it can cost literally thousands of pound to fix. With a petrol you are looking at a fuel pump costing 1/10th that of a diesel. Talking about main (high pressure) fuel pumps here not those that may have a little secondary diesel one in the fuel tank.
Then there are other common problems which fortunately or unfortunately depending what side of the fence you sit on are mainly (but not always) attributable to running a diesel.
Flywheel - DMF failing (then as a subsiduary cost beyond the DMF itself in replacing clutch plate, thrust bearing and slave cylinder - although not always necessary I agree). I do agree that a DMF failing in not just on diesels but the falure rate is far higher on a diesel.
Swirl Flaps
EGR Valve
DPF (EOLYS)
What i therefor conclude is over the space of a lifetime of a modern diesel compared to that of a modern petrol the diesel would prove more expensive to run in overall costs. Let's not forget that a diesel often cost a great deal of money more to buy in the first place.
I will also conclude that if you purchase a second hand diesel and only keep for a few years then change for a newer car where you don't encounter some of the excess expenses (DMF, DPF (EOLYS), fuel pump) then the diesel will indeed prove more cost effective. But this is in a 'just add fuel senario' or a high mileage runner.
Of course I've gone generic with what has been written above and not gone manufacturer nor model specific. I like both petrol and diesel cars, they each have their own characteristics that may or may not suit you individually. The choice is up to you and you alone - you pays your money you takes your chance!
I've tried to be objective here and give a genuine unbiased appraisal.
