Andretti Autosport is using a private test at Gateway Motorsports Park and a weekend off to put what are mostly regretful memories of the Honda Indy Toronto behind.

Three of the team’s four drivers appeared to be front-runners in Sunday’s race, yet each came home with a disappointing finish. The fourth driver, rookie Zach Veach, managed to turn a miserable qualifying effort into one of his best races of the season to finish a team-best seventh on the treacherous streets of Exhibition Place.

Championship contenders Alexander Rossi and Ryan Hunter-Reay started the 85-lap race fifth and sixth, respectively. Hunter-Reay, in the No. 28 DHL Honda, looked poised to battle for the win when he leapt three spots to third on the opening lap, but his day fell apart when he slid into the Turn 3 tire barrier on Lap 28.

“I had too much front brake lock and I just kept eating up too much track,” the 2012 Verizon IndyCar Series champion said. “I couldn’t believe it. I was running a comfortable third, probably would’ve finished second today, so that’s down to me completely. It’s a bummer.”

Compounding the issue was Rossi, running three spots behind his teammate at the time, ran into the back of a braking Will Power and damaged the front wing of the No. 27 NAPA AUTO PARTS Honda.

“(Power) had a bit of a problem going into Turn 3 and I misjudged the closing rate, so I had (to make a pit stop for) a front wing change that put me to the back,” Rossi explained.

It was only the beginning of problems for Hunter-Reay and Rossi. On Lap 34, Graham Rahal ran into the back of Max Chilton entering Turn 1, triggering a multi-car incident that collected Rossi. Hunter-Reay ran into his teammate, launching Rossi airborne. Both Andretti drivers continued and went back to pit lane for repairs that again included front wing replacements.

“Rahal got spun around and I stopped to avoid it,” Rossi said, “but then Ryan hit me and we got airborne. So then we changed the wing again – to wing No. 3 – and stopped another couple of times.”

Somehow, Rossi managed to stay on the lead lap and finish eighth. Hunter-Reay wound up a lap off the pace in 14th place. With points leader Scott Dixon winning the race, the Andretti duo lost valuable ground in the standings. Rossi sits third, 70 points behind Dixon. Hunter-Reay is fourth, 91 out of the lead.

“I just feel bad for this (No.) 28 DHL team,” Hunter-Reay said. “Last weekend at Iowa, we had a suspension issue (and finished 19th). This weekend I put it in the tires. Two weekends like that, you just can’t afford to lose points like that when you’re racing a guy like Dixon.”

As badly as Rossi and Hunter-Reay felt, the gut punch may have been even more painful for Marco Andretti. Despite qualifying 14th, the third-generation Indy car driver was confident he had a strong car and proved it in the No. 98 Oberto Circle K/Curb Honda. Andretti ran as high as second place and was solidly in fourth when he suddenly pitted for a splash of fuel as the white flag waved indicating one lap to go.

Bryan Herta, Andretti’s race strategist and co-owner of the Andretti Herta Autosport with Curb-Agajanian entry, said it was a simple mistake of not getting the car full of ethanol on the previous stop.

"At the second stop (on Lap 56), we didn't get the car full,” Herta told Autosport.com. “We thought we had enough fuel, but we didn't fill it up and it was totally a mistake from our side of the equation.

"We didn't know we were going to run out of fuel until we ran out, and Marco got the light on the dash telling him he was on the collector tank. We should have had plenty. It was a real shame because he earned that fourth and we lost it for him."

Andretti was rightfully distraught after seeing what would have been his second top-four finish of the season lost.

“We had to pit with a lap to go and my heart sunk,” said Andretti, who finished 10th. “I hate it for the Oberto boys. We had the top-four pace really all weekend, and the only time we didn’t show it was qualifying and the race. Really disappointed. We maybe had a shot at podium but definitely fourth.”

Veach, meanwhile, had fortunes the opposite of his teammates. Driving the No. 26 Relay Group 1001 Honda, the rookie methodically moved up the grid – not reaching the top 10 until Lap 40. After the find round of scheduled pit stops under green, Veach found himself in ninth place with 20 laps to go.

The 23-year-old Ohioan picked up two spots in the closing laps when Spencer Pigot contacted the wall and for Andretti’s fuel miscue.

“It was a heck of a fight today, honestly,” Veach said. “Starting 22nd, we knew we had our work cut out for us to get to the front, but we had great pit stops and great strategy. The guys did exactly what I needed them to do on the car on each pit stop, as far as adjustments, and it just came to us at the end.”

All four Andretti Autosport drivers tested on Wednesday at Gateway Motorsports Park outside St. Louis in preparation for the Bommarito Automotive Group 500 on Aug. 25.

The Verizon IndyCar Series returns to action on Sunday, July 29 with the Honda Indy 200 at Mid-Ohio Sports Car Course. Live coverage starts at 3 p.m. ET in CNBC and the Advance Auto Parts INDYCAR Radio Network. An encore telecast airs at 6:30 p.m. on NBCSN.