Using primary and backup cars back to back was once the easiest way to try different setups and to find if a particular chassis was better around Indianapolis, but to do so today, changing engines is required.
Now the focus has shifted for some teams to spend opening day refining and quantifying their backup cars before switching over to spend the month with their primary cars.
"You have a spare that's supposed to be reliably ready," Ganassi Racing General Manager Mike Hull told SPEED.com. "You work to make all your cars as identical as possible, but they all have their own personalities and you want to get them as close as you can with a day of running on them. We changed engines last night into our primary cars and ran them across the tech pad and will be out running first thing today."
Beyond tuning the back cars, Hull says there's a wealth of data that can be generated and used by running backup cars so early in the month of May.
"We have two spare cars for the Target team, and for the Service Central and Novo Nordisk cars," Hull continued. "You log all of the aero data from your backup cars, first, and with all of that data in hand, you can compare that to the primary cars and find if one is better than the other, for whatever reason. When the pressure starts to build when qualifying gets closer, at least you know what you have with your backup cars if you need to use them."