When a series releases a new spec for its cars that’s a significant departure from the past, the offseason is filled with uncertainty. A wealth of data collected from previous years suddenly tells teams much less. That is the situation facing Mazda, Cadillac and other manufacturers in the IMSA WeatherTech SportsCar Championship’s top Prototype class. They’re starting 2017 with a clean slate, with all-new cars.

For 2017, the highest class of prototype racing in America is switching to a new spec: Daytona Prototype International, or DPi for short. DPi shares many similarities to the international 2017 LMP2 spec, but it’s been tweaked to allow manufacturers (who provide significant financial and design support for many WTSC prototype teams) to use their own engines and branding.

Every single Prototype team in the series has a brand-new car to work with, leaving teams with little to compare the new car’s performance with. Such is the case with Mazda, who was hammering out some crucial test laps at Road Atlanta in their RT24-P prototype when Mazda Director of Motorsports John Doonan gave Jalopnik a brief testing update last week.

The team has been testing with last year’s engine to see if the new Riley Mk 30 chassis works. They already ran into an issue with gearbox cooling, which Doonan says the team promptly fixed.

For the most part, the drivers have been impressed by the new chassis, which is four inches narrower and seven inches longer than the last one. A more efficient aerodynamic shape has made the car faster both in corners and on straights. The drivers say it behaves more like an open-wheel racer than last year’s car, which should fit Mazda’s drivers who’ve come up through the marque’s Mazda Road to Indy ladder series.

“The predictability [and] the confidence of the base chassis, and the aerodynamic balance from [the drivers’] standpoints is a significant jump forward from what we experienced with our previous car,” Doonan said.

Because they’re running at Road Atlanta, the Mazda team is comparing their new car’s data with data from this year’s Petit Le Mans. Mind you, that 2016 car that ran at Petit is done—and none like it will compete against the 2017 Mazda RT24-P. But that odd benchmark is what they have, especially since all four full-season drivers testing the car were there last year.

While it’s good to see teams find and fix major reliability issues well ahead of the season, I can’t help but feel as if it’s weird that all of this early testing data sort of lives in a bubble. It’s one thing to feel as if a car drives well and is better than the last one. But you don’t know if the car you’re confident in is really going to win races based on your own feelings and comparisons with cars it won’t compete against.

The first time they’ll really get an idea of what the other cars can do is at later tests at Daytona. There, you won’t know what manufacturers’ fast laps look like as opposed to their slow ones yet, either.

There’s not much incentive for WTSC teams to reveal their true speed in public tests sooner than they need to. Last year, IMSA said that had been ahead of the Rolex 24 season opener. Now that Prototype has all brand-new cars, part of me knows there will be a lot of leisurely testing laps at the this year.

Of course, Mazda still needs to test their new engine, which all eyes are on for next year because of the team’s prior reliability problems. One upside is that they have one less variable introduced by running the old engine they know while testing their new Riley Mk 30 chassis. The downside is that—well, what if they don’t shake down all the issues before the season starts (again)?

Mazda remains optimistic, even if much of their engine shakedown will be at later, more public tests. Doonan described the 2017 engine as an evolution of their 2.0-liter turbocharged inline-four from 2016, with a few needed tweaks to fix various issues that plagued the car last year. That has been a fast engine until, for example, it . The new engine will be fully installed and tested for the first time later this month to get the car through IMSA’s official dyno tests at Daytona.

All of the WeatherTech Sports Car Championship’s Prototype-class cars are being retired after this…

Of course, IMSA isn’t the only place where teams are starting from a completely fresh, blank slate next year. Formula One has a major redesign as well, which means we should be on the lookout for sandbagging in public tests, and even suspicious-looking dudes hanging out in shrubberies around Milton Keynes.

As we saw with the new Ford GT and Ferrari 488 GTE this year at the, it’s hard to gauge a car’s performance ahead of the race it was designed for, where the team finally pushes their car to its absolute limit to get the win.

As a fan, I can’t wait. I have just as little of an idea of how all the other cars will perform as many of the teams do right now, and I enjoy it when races are hard to predict. Many of the strongest WTSC teams ran the old Daytona Prototypes, which are to drive than the LMP2-chassis DPis. Will they be able to adapt to the new cars, or will we seen some upsets?

2017 is guaranteed to be a strange year before it even starts, and that’s going to be a lot of fun.