DarthPuppy said:
I think part of the analysis involves gallons burned over the life of the vehicle. If a vehicle is driven 250k miles, but gets better mpg, it will burn fewer gallons. Fewer gallons of petroleum product burned would tend to translate to less emissions. Also, I think I recall that diesels have longer service lives, so on a fleet policy basis, diesel translates to fewer cars being built and then disposed of. They may have factored that in as well.
I'm guessing that EVs are taking a big hit due to assumed premature battery disposal issue since we don't yet have much in place for re-using batteries that have degraded past the point of tolerance for use in vehicle range.
Modern diesels are not nearly as reliable as they used to be, there are so many cars here that suffer dpf and dmf failure for instance. And there also not as economical as they are made out to be. People are now cutting out the dpf. Future emissions tests will most likely catch on to this practice.
Tax is lower on diesels here and people are buying them despite them being completely unsuitable for small mileage, but people are buying brand new diesel cars to save some money on fuel and yearly motor tax when in fact their greatest cost is depreciation, despite the diesel costing more to buy. Madness!
Modern diesels are too complicated with all the extra kit to reduce exhaust.
The euro NEDC is a total farce of a test and in no way reflects real life driving and so emissions must be higher.
Diesels may relate to lesser Co2 emissions but they emit far more toxic emissions than petrols and diesel exhaust has now been proven to cause heart disease and lung cancer.
So while you emit less co2 with diesels you emit far more dangerous emissions that are harmful to human health and the environment.
Mercedes has stated that making diesels in the not so distant future will be too expensive.
For quiet a lot of people buying a brand new electric car is much better for the individual and the environment than a brand new diesel car, A brand new Leaf costs less than a 1.6Diesel VW Golf DSG. yet only 45 electrics were sold on this Island so far in 2013.
There are longevity issues regarding the leaf battery and range which are an issue for most people, if Nissan can solve these by Leaf II in 2017 then maybe they will sell much better.
The diesel VW will cost a lot more to maintain, and there is the possibility of dpf and dmf failure which are expensive to repair out of warranty, and one of the reasons I will never buy a diesel again. Most diesels require timing belt replacements also, though so do a lot of other cars, but not the prius. Sure the VW will be a much nicer place to sit than a prius which could be the deciding factor in someone's decision to purchase or not.
However the cost of replacing a battery won't be cheap, so there needs to be some kind of money offered for the old battery. And getting to your comment on end of life batteries, well electric companies could use them for storing renewable energy or you could use it for storage if there were some kind of way to do this in the future.
So think twice before anyone falls into the diesel economy trap, imho a Prius is a far far more reliable car, it's complicated drive train has proved to be ultra reliable.
I regularly get 50-55 us mpg in my MK II prius, now with 105K miles, which isn't bad for 10 year old technology, there have been 0 faults. While this isn't the best as the best modern (very small) Euro diesels, it isn't far off what a lot of diesel drivers get in a car of equal size and power, granted it takes practice to get the best out of it but I know the Prius will suffer far less problems.
The prius is far bigger than a lot of small diesels with a good bit more power, if you think driving a car that gets 0-100 kph in 14 seconds good, then try one first. If you want a diesel with good acceleration then you'll still probably get a bit less mpg than the prius.