It could help a little. That tech page for the Feista gives CO2g/km for each vehicle and for the ones we’re comparing it’s either 80 or 87% of the ICE model. That’s something but remember these are for the EU vehicles that do not comply with the US particulate standards. And also remember that a significant increase in numbers of diesels would increase the price of diesel fuel dramatically, and possibly increase its well to wheel CO2 emissions. A discussion about that can be read here. The logic is that there is an optimal fractionation balance between diesel and petrol and that shifting more to diesel in response to greater demands risks introducing inefficiencies.
Hence the “apparently” in my post. Thanks for the clarification. 
The expense is the result of all the other drawbacks. Diesels are slower, so they require expensive turbochargers and/or larger displacements to perform as well as gasoline engines. They are dirtier and so require more expensive emissions controls than gasoline engines. If there were prospects of diesels getting relatively cheaper in the future I would say they’d be worth pushing, but there’s no real reason to believe that will be the case. I like diesels a lot more than hybrids, but realistically the cost premium and benefits of hybrids are similar to diesels, but they are an emerging and improving technology. Diesels do well in their high highway mileage niche, but they’re not the way forward.
Not necessarily. Currently, a typical refinery can swing the gas/diesel ratio less than 10%. If every car turned diesel overnight, there would be a heck of a lot of spare gasoline produced. It would be possible to build refineries to get a better diesel ratio (or make diesel from coal for that matter), but it’s a substantial investment for very little return in terms of carbon savings.
And, per my cite above, one likely to increase the CO2 produced per unit of fuel refined, as well as the price. That cite claims only a potential to push the diesel fraction up by 3-4% btw without pushing into inefficient refining methods anyway.
Interestingly, LOHD’s cite from the Union of Concerned Scientists argues fairly cogently against diesels. Per that cite diesels accomplish 15% less GHGs and 9% less oil use and the same money invested on improving the economy of a petrol vehicle would do better. The cite is six years old though and maybe some numbers could be updated. But one can look at the Chevy Cruze Eco, 42 mpg highway for $16,525 and consider their case.
Oh come on…next you will say it’s not equivalent because one has green seats and one has blue!
And what you haven’t mentioned is the higher torque that is going to make the diesel a more “fun” drive…buying cars is not always about the “rational”
Most big trucks are diesels , are they not? How do they compare to passenger diesels?
GM pushed diesels a couple decades ago. They sounded like loud clocks .
The VW Golf TDI wagon I am currently driving hardly has any diesel characteristics. In fact several colleagues did not even realize the cars we were given to drive were diesels.
They are quiet, virtually rattle free, with no noticeable exhaust soot unless you bury your foot with the revs very low. They do however have a rather distinct turbo whine at certain throttle and rpm combinations that sounds a bit Detroit Diesel, but can only be heard with the windows open and the radio off.
On the other hand I drove a diesel Ford Focus wagon that was not very enjoyable. It had too little torque or too tall of gearing as getting away from a stop on a hill or with a load could be a bit tedious. It also was much rougher than the VW at idle and under load.
Even so, the apparent benefits of diesel seem to be just that, an appearance and not an actual long term solution.
More fun facts to refute the ‘diesels are slow’ idea:
Diesels have won the Le Mans 24 hour race every year since 2006. But to be fair, the regulations for diesel and petrol cars are different and diesels still have a bit of an advantage. Plus Audi and Peugeot have much more money to throw into it than the petrol teams do.
The current diesel land speed record is held by the JCB Dieselmax, a streamliner using two 4 cylinder 5 litre engines based on their standard tractor engines.
There are yet more efficiency gains to be made from both diesel and gasoline engines.
An interesting article here discussing what the future may hold for Gasoline Direct Injection and gaining efficiency with GDI by making gasoline engines more diesel like (stratified charge).
And a paper here (warning PDF) looking at lean burn technology applied to diesel engines to improve efficiency by making them more gasoline engine like (homogeneous charge).
“A bit of an advantage” is a bit of an understatement. Le Mans rules allow diesels to be turbocharged.
Electrics are faster than ICEs. But speed is not what we are getting to. We are trying to save gas and cut pollution. How does the diesel do that? The electric is obvious .
Not just fast, but QUIET! I went to an American Le Mans Series race at Laguna Seca a few years back, and my buddy and I were astonished at the utter silence of the Audi Diesels. They’d fly by and all you would hear was tire noise and the sound of suspension components moving about. We dubbed them “the all-conquering golf carts”.
Nobody is saying diesels are slow in some absolute sense. They are just slower than an equivalent gasoline engine.
With Le Mans racing, diesels have an advantage because better fuel economy means fewer pits, not because diesel has some intrinsic advantage over gas engines. The rules had to be extensively tweaked to allow diesels to be competitive-- diesels are allowed an extra 1.7 liters of displacement and much higher boost pressures. If the gas engines were allowed the same, they would be dangerous 1000+ HP machines that would leave the diesels in the dust.
So, to sum up, diesels can be faster than gasoline engines. But I could have told you that with my old Benz 240D which was (slightly) faster than my 2-cylinder Deere lawn tractor. But in order to make a diesel that performs the same as an equivalent gasoline, it costs more. On a production car, this means you are going to either pay more for a diesel or put up with slower performance.
Yet despite being turbo charged and having larger displacement, the Le Mans diesels still got better fuel efficiency.
Doesn’t that say something about an “equivalency” argument?
I remember an Alfa Romeo diesel winning its class at Bathurst - the engine was stock, it still got over 8km / l over a 24 hour race. What stock petrol engine is going to do that?
And that goes to the heart of the “diesel advantage”. They can render more power, more torque with lower fuel use than a similiar vehicle (note vehicle, not engine) using a petrol engine.
But turbo on a diesel is the standard state of affairs. You won’t find a non-turbo automotive diesel anywhere. In my BMW example the ‘standard’ diesel is roughly equivalent in power to the ‘standard’ petrol while being more efficient and cheaper in the long run. In Le Mans LMP1 they aim to get roughly the same power out of each engine type (about 650bhp if I remember right) so they treat a 6 litre petrol the same as a 5.5 litre diesel and a 4 litre turbo petrol. The diesels are carrying an additional handicap this year of a 30kg higher minimum weight and a 10% smaller fuel tank.
Which makes them a pain to take pictures of. I never caught a good shot of the Audi or Peugeot at the Ford Chicane but got plenty of the Corvettes since you could hear them as they came thru the Porsche curves. The Aston Martins with the V-12 made a nice sound too.