Jay Howard led Schmidt Peterson Motorsports to the top of the speed charts on Thursday as practice for the 101st Indianapolis 500 continued, with McLaren driver Fernando Alonso ending the day fourth-fastest.

Howard has not raced in the Indy 500 since 2011 when he crashed out early on, but announced his entry to this year's race as part of a joint effort between Sam Schmidt and recently-retired NASCAR star Tony Stewart.

The British driver hit a tow off multiple cars early in the day to record a best average lap speed of 226.744 mph, giving him P1 at the end of the day.

Andretti Autosport enjoyed an impressive day as four of its affiliated drivers finished inside the top 10, led by Ryan Hunter-Reay in second place. Marco Andretti was third, while Alonso's progression continued as he completed 96 laps en route to P4 at the end of the day.

Josef Newgarden led Penske's charge in fifth place, but was able to complete just 35 laps after suffering the first major crash of practice. Newgarden spun into the wall at Turn 1 and was taken to the medical centre where he was duly cleared by the staff on-hand.

Sage Karam took sixth place ahead of Charlie Kimball and Oriol Servia, while Takuma Sato was ninth for Andretti. Sato did, however, lead the no-tow speed charts ahead of Kimball, while Sebastien Bourdais ended up P10.

Teams made the most of the dry conditions to complete plenty of laps - over 2,000 through the field combined - ahead of the predicted inclement weather later in the week, with a mix of both race and qualifying simulations being completed.

Practice continues on Friday at Indianapolis Motor Speedway ahead of qualifying, which takes place over Saturday and Sunday.