The hover jets let it effectively turn into an ACV. Titans Wiki even links a ground effect vehicle. It isn't flying it is for use over rough terrain. Useful in other situations? Sure, but here it isn't relevant. Herbie, can drive on walls. That is a way better traffic hack than ignoring rough terrain.
The Ninjas live in New York, if I had to guess because of their connection to Daredevil in origin, somewhere in Manhattan. There is plenty of traffic and plenty of walls for Herbie to get an edge here. Even assuming both cars start in a different Borough on a different island, the T-Car does get a nice bridge skip, but there is so much traffic in New York City that Herbie's wall driving is more utility than getting to skip one bottle neck.
Also I doubt the GPS of any quality gets you to a manhole cover or relevant storm drain faster, but the GPS is not listed as part of the T-Car per the wiki. Far more likely is that Cyborg has his own built in GPS and the T-Car relies on that. Herbie and the T-Car are using the same GPS here. Herbie has not gotten lost when traveling beyond San Francisco and LA. He has gone to Monte Carlo and then across France in a race, Puerto Vallarta, Mexico, Rio De Janaro, Brazil, and Las Vegas.
Finally, Cyborg's T-Car is (according to the Titans wiki) is a 2005 Infiniti FX35 heavily modified. This gives Herbie way better dimensions for parking and delivery. Herbie is almost 3 feet shorter in length and over a foot less wide. Finding a tiny cramped space in New York is a problem and one Herbie is better equipped to deal with.