Luxury cars? I had a 2005 Honda Civic 2dr I bought new, (far from a luxury car) PW, PL, AC, Cruise, 1.6l 4 banger, got about 45mpg. The same car without all the bells and whistles, was only about $800 cheaper, and got the same gas mileage, if you didn't use the AC, even with the AC it still got 38mpg....better than most vehicles on the road today.
As far as public transportation, here in Canada, only about 20% of the population live in the city, and within range of a bus, or train, the rest live in areas where there is no public transportation, so you have no choice but to drive.
Park and Drive? What is that? Sure the big cities like Ottawa, Montreal, Toronto, Vancouver have it.....but outside of that, it doesn't exist. Even then it only runs a couple of times in the morning, and couple of times at night....its just not a practical form of transportation to most.