Heh, reminds me of the saying: An Englishman thinks a hundred miles is a long way; and American thinks a hundred years is a long time.

Houston to Austin seems to take 50 minutes by flight vs. 2 hours and 30 minutes by car. That's not the best convenience ratio for a domestic flight (going between the two largest cities in Denmark is 40 minutes by air vs. over 3 hours by car), and it's certainly more expensive...

However, whether it's more polluting actually depends on a lot of things. Comparing a fully booked, modern commercial passenger plane vs. a car carrying a single person usually has the airplane coming out on top (heh). A modern car with all seats occupied beats the airplane though.

(A naturally aspirated V8 without direct fuel injection leads to a divide by zero in any efficiency calculations.)

Just remember to leave early enough to arrive at the airport 90 minutes before your scheduled departure time ;)

And don't forget to factor in that IAH is a 20 mile drive from downtown Houston, and AUS is another 10 miles to downtown Austin! (Combined, that's about 1/5 of the driving distance between the two cities.)