Very much different.
Not Your Father's Diesel
http://www.forbes.com/2009/05/21/diesel-cars-future-lifestyle-vehicles-diesel-cars.html
2012 Diesel Cars in USA: Here’s the Lineup
http://www.practicalenvironmentalist.com/automobiles/2012-usa-diesel-cars.htm
We looked at diesels when we bought a car last winter, but the mileage savings just didn’t seem to cover the extra cost. We ended up buying a Volvo XC 70, T-6 AWD, that gets 27 mpg, regular gas, not high test.
Our needs are a little different than most peoples, and this vehicle was a perfit fit, literally. My husband is 6’6, and I am 5’4”. We try cars on before we test drive. At the time, I was driving a 1995 850 turbo wagon that we had for 16 years without any repairs, ever. We just had it serviced regularly and replaced a few things that just wore out (and those stupid chips for the emission monitors), but I was getting nervous about long trips and just wanted a new car, with cup holders, at least. So, 27 mpg and the most comfortable seats of all the luxury cars, along with cool blue tooth technology, and I’m happy. I haven’t tried it in the snow yet. I had the ‘95 fully detailed, even the engine cleaned and the windows tinted and passed it on to my husband, who drives a company car. He’s happy and I’m happy.
In 2013, Audi is bringing a 3.0 TDI in the A6, A7, A8, and Q5. Output on the order of 240 hp and over 400 ft-lbs. Q5 mules getting 40 mpg on the highway at 80.