If diesel cars are cheaper to run then why haven't they fully replaced petrol cars?

Many modern petrol cars average 50mpg. Eco cars don't cost much to tax. You need a larger diesel engine to produce the same power as a petrol one and a turbo which is an expensive replacement. They are more expensive to buy and servicing isn't as straightfoward. Diesels are a nightmare to jump start as well, linked with carcinogenic emmisions, older ones are noisy.

Unless you are doing over around 15000 miles a year, which is well above average, a diesel car will be more expensive to buy and run - its a fact, so get over it On top of that many owners do not want to be using smelly old diesel, prefer the way a petrol engine performs and do not want to listen to the clanking old diesel engine So why do car manufactures still make lots of expensive to run petrol cars? - because for lower milages they simply are not and because most of us actually like them Incorrect facts in your question lose you all credability. We have a sporty 1.6 that costs less than £150 a year to tax. There is no point having a diesel that runs to 250000 miles when all of the running gear on the car is well worn out and beyond economical repair well before that. Have you seen how much it is to replace the dual mass flywheels and anti polution systems in modern diesels? probably not otherwise you would not be coming out with all this rubbish.

They might well have if the government had not increased the tax so much on diesel. Up to 30-40 years ago diesel was much cheaper than petrol, and also potentially more environmentally friendly. However, once diesel cars became more popular the tax was massively increased under some pretext about there being more soot in the emissions.

The fact of the matter is that modern diesels are hobbled by EU rules, rules that were designed for long distance trucks, not modern cars that spend most of their lives in towns. For example. I currently drive an old school 5 cylinder 2.5 litre TDI V70 phase 2 & it averages 43mpg. More modern D5 & 2.4D produce 41 & 35 mpg respectively. A backwards step in terms of economy. The older D5's didn't even give you that - 34mpg on average - firmly petrol territory. Both the D5's & 2.4D's are useless on the local runs because they have DPF's (diesel particulate filters - as mandated by the EU) that clog up, unless used on a decent motorway trip. I have no such faults in my old diesel with an engine sourced from an Audi 100. Small engined petrol cars have now caught up with diesels on most fronts, especially environmental as petrol is simply a cleaner fuel & does not require special filters to clean up it's exhaust. Modern diesels also have another problem caused by the EU - the diesel additive AdBlue/BlueTec, for trucks this is not a problem, they have an easy to fill tank on the side of the chassis. Cars do not, in fact to refill a car you are looking at a bill of hundreds of £'s. That is a lot considering all you are putting into the cars additive tank is effectively piss & water. Then there is the stigma of running a diesel, especially on a cold start it sounds like you are driving a tractor, even when you start a modern one. Petrols cost less to buy in the first place. Yes, if you do mega mileages on motorways & pull large things modern diesels are make sense, for the driving that most people do, a small petrol is lighter on the wallet.

Modern diesel engines cost about £1,000 more to build than the equivalent petrol engine, so the cars cost more. The equipment necessary to make a diesel engine meet the latest emissions regulation is to blame, and has also increased the servicing and maintenance costs of diesel engines. This means that for a low-mileage driver a new diesel car will be more expensive to buy and more expensive to service and maintain than the equivalent petrol car. For a high-mileage driver a diesel may make finance sense compared to a petrol, but the savings are less than they were a few years ago. Future emission legislation, combined with advances in petrol engine technology such as that in Ford's 1.0-litre EcoBoost engine in the Focus and C-Max, and planned for the next generation of Mondeo, mean that the economic benefits of diesel are diminishing, and manufacturers are preparing for an increase in the proportion of petrol cars sold in Europe over the next few years. In fact diesel may become virtually non-existent in very small cars in the next 5 years or so, as the costs and weight of a Euro VI compliant engine in a small car (or even a medium car) may not be justifiable by most buyers. For example, 10 years ago Volkswagen offered a choice of a 1.7 non-turbo or a 1.4 turbo diesel engine in its Lupo A-segment car, but today's equivalent, the "Up!" doesn't offer any diesel engine. In larger cars, where the cost and weight of the diesel engine are smaller proportions of the overall cost and weight of the car, and buyers typically drive greater distances, diesel is expected to remain dominant in Europe.

Petrol driven cars are usually less noisy and perform better. However, since I replaced my Audi TT FSI with a diesel powered Q3 I have found that these new diesels are much more powerful than they used to be and perform extremely well. With my TT I got around 30mpg but with the Q3 I am achieving about 50 mpg and in all honesty I am getting from A - B just a quick.

There is something in what you say. Diesels CAN be more economical to run if you do enough miles and enough long runs. The new turbo-diesels give acceleration that is comparable to a petrol engine. They are better at hills than comparable petrol engines too because diesel produces more grunt (torque). I choose to drive automatic cars for which diesel engines are ideal due to their higher torque at low revs. The downside is that I do not cover enough miles or make enough long journeys for a diesel car to be viable. The initial price plus higher maintenance costs plus shortening the life of the expensive particulate filter makes them a non-starter for me. For me, they would not be cheaper to run .... beside which my wife objects to cars that makes that much engine noise. Driving schools like diesels because their cars cover many miles and because of diesel's higher torque. It makes the cars slightly harder to stall when clutch control and gear selection is not as good as it could be. Whether the learner would actually be as competent to drive a petrol car after passing their test is questionable, but that's not a criticism of diesel cars. As a car buyer, I look for the whole-life cost of my car and how pleasant it will be to own. With my current and forecast driving needs, diesel would not be a sensible option. Car insurance costs are related to risk. As some diesels are slower, less powerful, heavier and less appealing to high risk drivers, it is perfectly plausible that some diesels can be insured for less than some petrol cars. Boring cars are less risky for insurers so they charge less to insure them, whether petrol or diesel.

Because drivers who have always driven petrol cars are prejudiced against them. Older diesels were indeed smelly, noisy and expensive compared to petrol versions. However modern diesels are clean due to exhaust filters, quiet, and much more pleasant to drive. They have much more torque which makes for relaxed driving. VW make a 2 litre diesel that churns out 184 bhp yet still exceeds 67 mpg. Ok they are a bit dearer than petrols but they last much longer and driving through a puddle doesn't snuff them out.

All you say is so. My 1.4L diesel car has averaged 52.4mpg since I bought in in mid-2010. The CO2 emissions are only 116g/km, so my VED is only £30. This year's insurance is just under £200. Diesel engines generate maximum torque at relatively low revs. Mine gives 160Nm at 2000rpm. This is very useful in town driving. It also cruises at 70mph at 2750rpm. On paper, to 30mph, it should out-accelerate a friend's BMW Z4. OK, from then on, I watch it disappearing into the sunset. However, when diesel cars go wrong, they can be very expensive to fix. I've just paid £1,200 for a new diesel particulate filter (DPF).