About 3.5 hours.
MapQuest estimates the driving time as 3 hours and 22 minutes.
Tulsa
It is 205.91 miles according to MapQuest.
Air miles from Oklahoma City, Oklahoma, to Dallas, Texas, total 191 miles. That is 307 kilometers or 166 nautical miles.
My guess is Oklahoma City because Dallas is farther and i think Denver and Albuquerque may even be closer to Amarillo then Dallas is.
206 miles, 3 hours
Oklahoma City is further from Dallas than Dallas is.
It requires 7 hours of driving time.
It is 7.5 hours.
Oklahoma City is north of Dallas.
From Dallas, it's about 206 miles
8 hours