Alexander Sims topped the timesheets in an uninterrupted Free Practice 1 session in New York City on Saturday morning.
The BMW i Andretti Motorsport driver posted a best time of 1:09.959 on a full 250 kW run in the closing stages to go 0.018 seconds quicker than Sebastien Buemi’s Nissan e.dams entry.
Robin Frijns’s Envision Virgin Racing entry placed third ahead of Jean-Eric Vergne’s DS Techeetah.
Championship leader Vergne had a fraught session as he endured two lock-ups at Turn 6 and also brief contact with a wall midway through the 45-minute session.
Sims’ teammate Antonio Felix da Costa claimed fifth while the Portuguese’s fellow title contender Mitch Evans took his Panasonic Jaguar Racing car to sixth.
All 22 drivers set flying laps, but several drivers had trips down the Turn 6 escape road.
Da Costa, Buemi and Audi’s Daniel Abt all experienced locking-up incidents at the left-hand corner.
Free Practice 2 will get underway at 10:00 a.m. local time for an additional 30 minutes of track running ahead of qualifying which begins at 11.45 a.m.
RESULTS: Free Practice 1