Mayor Michael Bloomberg urgently wants to get the Taxi of Tomorrow up and running on city streets before the checkered flag falls on his administration. But as he puts the pedal to the metal, City Comptroller John Liu is trying to slam on the brakes.

Why? Most New Yorkers are eager to see the new taxis start their scheduled rollout on Oct. 28. Known officially as the Nissan NV200, the taxis promise more legroom, ports for electronics and other amenities.

Yet Liu is refusing to register the city's contract for the taxis on the grounds that it doesn't comply with the Americans with Disabilities Act. He wants all cabs to be wheelchair accessible, and the base model for the NV200 is not. The city says Liu has overstepped his authority and that it'll go forward with the October start..

So Thursday Liu took the argument to a new level. He sent out a news release exhorting the mayor to abandon his "failed" taxi plan and offered one of his own. It would broaden competition among manufacturers in hopes of making the whole fleet wheelchair-accessible.

But is he speaking as comptroller, or as a candidate for mayor whose prospects for victory on Tuesday seem to be slipping away? We'll go with choice No. 2.

A couple of points:

The Taxis of Tomorrow are being built now in a Nissan plant in Mexico. Meanwhile, not only will Bloomberg be gone on Dec. 31, Liu will be out of the comptroller's office then, too. So short of making noise on the campaign trail, it's hard to see one shred of practicality in his plan.

The city already has a strong plan for better wheelchair access. Disabled passengers can summon an accessible taxi to their location now with a smartphone app -- but the wait-time averages about 14 minutes. The city's Taxi and Limousine Commission says that delay will diminish when it adds 2,000 new wheelchair-accessible cabs to its 13,237-taxi fleet. It's preparing for the medallion sale now.

Long term, the TLC wants to see a fleet that is 20 percent accessible and app-friendly. Liu needs to get out of the way and let progress take its course.