Yep, 2-3 hrs max. We just drove using the toll road. It was at night though. Very efficent, no problems, smooth driving. The big trouble was at the border crossing in Laredo Bridge I and Colombia during the holiday season. Crossing time in Bridge I: 6 hrs at night, sitting down with a barely moving line, to end merged in another because the cops closed one and put everybody in one... the bad side is if you cannot merge there, they send you to the beginning. grr.. Moved to a different bridge - Crossing in Colombia bridge: 16 hrs. Hated it but it was less bad that the people in the first one.
The city map the hotel and car rental provided were the exact same one! And not very good. Try to get a map before you get there. I know its tough to get one on the net but buy one if you plan on staying there for a while. Like in any other city you can get a handle of the roads and figure them out eventually. But save yourself the agony during the learning curve and take a map with you. Hotels and other turist areas all have the same basic map and like I said before its not very good.
This is a city with almost 3 million innhabitants, so parking your car could be a difficult problem, specialy in commercial centers or cinema centers. You can find heavy traffic 7:30-9:00, 12:00-14:00 and 18:00-20:00 hrs.
There are a couple of options to take. First you can fly there and second you can drive there.
When driving it is a strait shot down Interstate 35 which changes to 85 in Mexico.
The best thing may be to rent a car. This city is not as mucha as a tourist area as some of the more popular vacation cities.
Other than flying or taking a bus (first class Mexican bus lines are excellent), from the North the best way to come is by car from Laredo, Texas to Nuevo Laredo, Tamaulipas which is across the river. Traffic on both sides is very slow at the border inspections so be prepared to wait. The photo is a rare momment when traffic was actually moving on one side of the bridge. Congestion is the rule, so plan accordingly.
Whatever you do, even if it is first class, NEVER take the train.
Take the autopista. This 'couta' road is excellent. Beware of the 'libre' roads. They are longer, slower, and congested with large slow-moving trucks.
Car, subway, or just walk around.