McLaren sporting director Sam Michael has revealed that F1 teams are on the limit to be ready in time for next season.
With the sport undergoing a major overhaul for next year's Championship, work on the cars is well underway as many teams switched focus months ago.
But despite their efforts, they are in a race against time to be ready for the first pre-season test at Jerez on January 28.
"Absolutely, it will be on the limit," Michael told Autosport when asked 'how much of a challenge it is going to be for teams to get ready for the Jerez test.'
"These days we have simulations, stress analysis and dynos that are much more sophisticated than when we had the last big rule changes, but you are still upsetting your systems that are quite methodical and procedural.
"Teams now have operational procedures to make sure they don't make mistakes, and almost all of those will go in the bin [for 2014] and we will have to start again.
"That is why you will see variations next year. All teams at all ends of the grid will have problems getting to grips with the new systems."
The McLaren man expects all the teams will want their new cars out on track for the first test as, even though in the past some teams have run their old cars, he says there is not a single advantage to doing that.
"I'm not sure what advantage you would get from missing it [the first test]," he added. "If you push back a test, you normally do it for more wind tunnel testing - you don't do it for reliability.
"So looking at the chassis, you will not get an advantage of working on it longer.
"Of course you could do three weeks more work on front wings and diffusers, but you will bring an update package for the first race anyway so there is no advantage.
"I personally think you don't want to miss those tests. You want to be out there all the time."