Awesome. Love the name/domain. Beautiful UI that will clearly keep getting more so. Couple of thoughts re design: 'Love sharing great things to do?' box should line up on the right side with the right side of the boxes above (using Safari.) I'd also try making the width of the sign up bar at the bottom the same as the footer bar (Home | What is This?, etc.) Keep up the sharp work.
I'm no expert but I believe the sulfur content is higher in North American diesel, but that's not too hard to handle, I think that's the old excuse and there are fairly clean ultra low sulfur diesels you can now buy. To pass California emissions, you need to put some sort of aqueous urea tank in to the exhaust system like an AdBlue or BlueTec and those cost a couple thousand dollars (I want to say it's like $3000 on a diesel sedan like a Subaru or the 320D)
I'm not sure why the costs are so high, it may be a patented technology, there isn't anything terribly exotic in it though.
If you can legitimately get in the 40-45mpg range, it's still a pretty good deal. A Lexus RX hybrid still only can get like 30mpg.
Because there's a negative perception hump to get past in the usa. I tried suggesting a diesel, and everyone complains about how dirty it is and other myths.
There are diesels that get even better millage, like the Audi A2 with a mileage on it's diesel model ranging from 80 to 120 mpg. I never understand why car manufacturers don't make aerodynamic body designs for their cars. A honda insight with a diesel engine gets similar mileage.
It used to be difficult - to the point of being impractical - to make a small diesel car run cleanly. IIRC, the technology really only arrived about 5 years ago. Also, large trucks belching plumes of black soot were pretty common until recently, and this is how many people here still think of diesel.
Also, modern refining technology allows a greater percentage of a barrel of oil to be made into gasoline, and the low-sulfur mandate has also added to the cost of production.
Diesel fuel used to be in some sense a waste product and thus historically was cheaper than gasoline. It's only been within last 5 years or so that diesel has been consistently more expensive than gasoline, at least in the US.
