I used to be super impressed with overseas diesels until I learned the difference in an imperial gallon and a US gallon. There is a considerable difference. Also the cost of diesel per gallon is much higher than gasoline and offsets the 10mpg better fuel economy.
1 imperial gallon is 1.20095042 US gallons.
If you calculate the 50mpg in the US, it is a womping 60mpg in the UK!
For a gas burner, that is really good.
Now for US diesel.
I drive a Prius. Average fuel economy for 169 fill ups is 41mpg (49.238944137UK).
Lets look at the nice Jetta TDI. They get an average of 45mpg (54.042743564999995UK)
With Gas prices at $3.499 and Diesel at $3.799, there is a $0.30 hike in fuel cost per gallon.
If we calculate the difference we come up with:
Cost per year driving 25,000 miles (I drive 25k-30k per year)
Diesel 45mpg @ $3.799: $2,106
Gas 41mpg @ $3.499: $2,128
Even though it gets 5mpg better economy, it only saves $22 per year. Not a huge savings, and diesel uses more barrels of oil to produce. Only 12.7 barrels of oil are used to produce the needed gas, and 14.3 barrels of oil are needed to produce the needed diesel for the same 25k miles.
Another argument is the cost of maintenance. Both vehicles are pretty costly to maintain. Prius batteries are expensive, costing $1500-$3000 for a rebuilt battery. On the other hand, the diesels use high pressure fuel systems. Injectors are expensive and so are fuel pumps which can also be in the same $1500-$3000 range.
Prius batteries have proven themselves to be pretty reliable. There's Priuses out there with over 300,000 miles on the original batteries, and they're still going strong. I really don't think that a $3,000 battery replacement on a Prius is a factor.
You make a good point about the difference in gallon size, but im sorry to tell you the difference you get in diesels is far better than you quote. Diesels are getting more and more economical every day due to strict Euro emission standards, in a recent drive, the Ford Fiesta diesel got 108 MPG, thats over 80 US MPG. Even a hybrid can't match that!
And maintenece is lower too, the service intervals tend to be longer and many diesels can go 30,000 miles between oil changes, yes thirty thousand! Factor in road tax which we pay in the UK too, and you can see why diesels are.so much more popular outside the US.
Euro emission regulations are the main reason, getting stricter and stricter, the easiest and quickest way to emit less carbon is to simply burn less fuel.
In the last few decades the emissions regulations in the States have been to reduce hydrocarbons and NOx. But only by paying attention to ppm, not total output. A 7L V8 can fit this standard as well as a 1L 3 cylinder...that's what happens when corporate lobbying is a free for all your government.
Yea I love how the government taxes cars and trucks, and yet the big consumers like air liners pay very few taxes in comparison. A jet uses the same amount of fuel just to take off as a normal 40 MPG car would use over 160,000 miles. Ridiculous...