Rode cross-town on 10th St to 4th Ave, across 14th St, continued on Park Ave, to 65th St, where I turned west. Rode across the park on the car road, not my plan, but it worked out. Then I stopped to take in the view on Central Park West and somehow the trip got stopped. That much was 4.9 miles.
Then I looped south and around the bottom of the park, swung up the east side and rode all the way up to the top of the park. Saw a beautiful swimming pool, huge, and not too crowded. This is where I discovered that I had had the malfunction.
Started up EveryTrail for the second leg. Went across 110th to Riverside Drive. Then headed south, crossed over to the greenway at the boat harbor, then headed south down the usual route. Stopped at the heliport to rest and shoot a video of a helicopter landing.
The second part was 7.1 miles.
Looks like the uncounted part of the trip is almost exactly 4.0 miles.
PS: Just noticed Google can send maps to cars now.