While the Firestone Grand Prix of St Petersburg may mark the start of a new era for the IndyCar Series, the new-look aero kits that will be introduced have a more pressing deadline than the 29 March event.

Aerodynamic bodywork designed, manufactured and supplied by Chevrolet and Honda will differentiate previously identical cars by their new shapes, with the manufacturers having designed speedway and road/street course/short ovals aero kits for the Dallara IR-12 chassis.

Manufacturer track testing of prototype components opened on 6 October and continues through to next Sunday (18 January), which is also the date for homologation. Production will then ramp up to meet the 1 March deadline for one road and street course/short oval kit to be delivered to each entrant. The speedway aero kit, according to the IndyCar timeline, will be delivered by 1 April.

The initial track test for teams is scheduled for 16-17 March at Barber Motorsports Park, while the 99th running of the Indianapolis 500 on 24 May will mark the debut of the speedway aero kit.

"Differences between the 2014 Dallara chassis and the 2015 aero kits and between the Chevy and Honda aero kits will be quite easily spotted by an interested fan," IndyCar director of aerodynamic development Tino Belli claimed, "Especially to someone who is interested in technology, they'll see many differences between the cars although, at speed and with different colour schemes, it might be more difficult to see the differences. But it's certainly not going to be a spec car, and it's not spec even within the Chevrolet or Honda environments. The Chevy might not always run in exactly the same configuration between a Penske and Ganassi car, and the same with Honda between, say, an Andretti and Schmidt Peterson Motorsports car, because teams will have options."

Development is frozen as of 18 January, with IndyCar requiring the CAD files, the weights of the components and layer books associated with each kit. Although the series organisers don't have to have an actual component in its hands by next Sunday, it has to have all of the designs, which will then be locked down.

"The only thing the manufacturers can do afterward is if they have some sort of reliability issue or if they could prove they could save significant money by altering a construction technique to save money they can ask for a concession," Belli explained, "But the component won't be allowed to be any lighter and we want it to have similar stiffness."

Despite the homologation process, 'legality boxes' - or areas open for development by manufacturers - will exist in 2015?

"The engine cover, sidepods and rear wheel guards are common between the speedway and road/street course/short oval packages," Belli noted, "On the speedways, the manufacturers can do a new front wing main plane, rear wing end plates, front wing end plates. Teams are allowed to use optional components that fit to the sidepods, engine cover and rear wheel guards such as winglets and flicks.

"The teams will have quite a lot of things they can play with if they decide that they can come up with a better solution for their particular requirements and their driver or car set-up. The car set-up is not only going to be a downforce level like a wing angle, springs, shocks, toe and camber. If a particular type of mechanical set-up needs an aerodynamic solution, they can try what they like.

"We believe there will be a reasonable number of components that the manufacturers will homologate as optional that a team could investigate to see what could give it a better solution on a particular racetrack. An example is the Indy road course, which because of the length of the straights is a low-drag racetrack. You can imagine teams coming up with a hybrid speedway/road course solution. They can't put on a speedway front wing on a road course, but they could perhaps use speedway sidepod options.

"Another thing we're allowing is all of these optional components can now be changed between qualifying and the race. A team could decide to go for a super low drag qualifying set-up and use the newness of the tyres to try to get the speed and then revert to a more high-downforce race set-up, which could mean a change in some of the components on the sidepods, wheel guards and engine cover. For a long time, we had what you qualified with is what you raced.

"The same will be true for the Indy 500 with the optional components. In qualifying for Indy, you might put on all your lowest drag optional components or choose to emit components, and then for the race you might decide there is some sidepod winglet that might give you better handling characteristics or is more efficient.

"On the road course in addition to the sidepods, engine cover and rear wheel guards is the front wing flaps and end plates, and the rear wing end plates. The rear wing is a standard Dallara main plane for all events except for the Indy 500, during which teams can choose between the Dallara or their manufacturer's main plane. The engine air intake will be different from the Dallara chassis, too."

There will, however, be limits on how many times components can be improved.

"From a performance point of view, except for the sidepod and engine cover that have to remain fixed for two years, all of the other components are up for being upgraded,2 Belli confirmed, "But they only are allowed to upgrade three legality boxes total in a two-year period.

"Currently, they can choose to homologate a new component in one of the three boxes any time from the beginning of the 2015 season to the end of the 2016 season. If one manufacturer feels it is behind in a particular configuration, it can bring forward a box to try to catch up earlier. If you're feeling confident or comfortable, you'll want to delay upgrades until after you see how 2015 pans out with all the different racetrack configurations we go to. The components that get changed, the old components are grandfathered so teams can still choose to continue to use those components or use them as spares.

"Our task is to make sure that the component as homologated doesn't get altered by either the manufacturer or team. We want the bodywork run as the aero kit manufacturer designed it and manufactured it. We'll be checking the weight of components along with the shape and stiffness of the components. Like the current technical inspection, there will be a combination of jigs and fixtures, load tests, maximum and minimum height dimensions and then we'll continue with the laser scanning that we tested last season so we can compare our record of the CAD of components against the car any time."