More diesel in the US would be much better. Especially since right now it's cheaper than premium and not much more pricey than regular. In New Jersey which has the cheapest gas in the country, so cheap that by law all gas stations have to be full serve, diesel is 24 cents cheaper than premium and only 6 more expensive than regular using credit of course.
I wish I saw this thread earlier to jump in on it. I currently drive 2 diesel vehicles and I love them. The third, Audi Q5, when the US gets the diesel version it will probably be swapped. Diesel makes so much sense for a daily driver. The torque is right there when you need it for instant passing power. It also provides great gas mileage and is more efficient when idling. We all know due to thermodynamics that diesel is a much more thermally efficient fuel too. As an engine it may not be as much fun because you can't rev it up and the power curve doesn't get stronger but it works well.
Our BMW 335d is amazing, the best car i've ever driven. So much torque and power. The car id ridiculously fast and can easily be tuned with a chip to go even faster. It is slightly slower than a 335i. The engine is very smooth and sounds great. very powerful and returns great mileage. If driven gingerly it can put out over 40mpg. It easily hits 36mpg. Driven hard highway i get around 32mpg. I usually get 34-35. in the city it gets high 20's
My sisters Jetta TDi is also really nice. for a small engined car it doesn't feel like a 4 cylinder, has lots of power when you need it and it pulls great on the highway. Easily getting 40 mpg and never below 30. It makes so much sense.