NASCAR has ordered the end of direct communications between the drivers and spotters of different teams during the Daytona 500, in a further measure to cut down on the much-criticised phenomenon of two-car tandem racing on restrictor-plate superspeedway races.

The measure, first rumoured in mid-December, will stop drivers from being able to talk to each other to co-ordinate their runs and their drafting strategy.

Drivers have been able to talk directly with up to 20-30 others under the previous system, but the new rules mean that they will now only be able to speak to people within their own team. While the new regulation is being brought in to specifically cut down on tandem racing at Daytona and Talladega, it will apply to all Sprint Cup races in 2012.

The ban will make it more difficult to arrange drafting/pushing deals in advance as well as making them work on the track, since the driver at the rear has almost no visibility and replies on constant feedback from the car in front to make the strategy work. Without direct driver radio communications, the car at the back will also no longer be able to tell the car in front when his engine water temperature is climbing and he needs to switch positions.

Sprint Cup series director John Darby insisted that the move was as much at driver request as anything.

"There was a point where it got so confusing to them, that they actually lost focus on what they were doing," he said. "Matt Kenseth said it the best to me in the garage, [that he supports] anything that NASCAR can do to help us get back to one against 42 others."

"The teams will still work with inside the rule, whether it's spotters on the roof, swapping notes back and forth. There will be plenty of communications going on, and the drivers will be almost as aware as they were," he added. "It just seemed like that would be helpful to unclutter the airwaves a little bit, if you would, and make the communications more point-blank and direct to within the team."

"I don't think it'll be a big deal," said Dale Earnhardt Jr., who wasn't expecting the move to make much difference in practice. "Pretty much everybody is working with team mates anyway. I don't think they're going to limit that. ... When we first started tandem drafting, you might end up working with somebody outside of your company, but then everybody sort of got a little strict on who they were going to work with and how they were going to do it, and they stuck with that plan the entire races."

The decision was confirmed on Thursday as teams got the first of three days of pre-season testing underway at Daytona International Speedway.

Teams are testing their new electronic fuel injection systems, as well as adjusting to a collection of regulations also designed to stop two-car tandem draft/push racing, including the capacity and placement of radiator grilles, softer springs, a smaller rear spoiler and changes to the size of the restrictor-plates that teams have to use at superspeedways.

However, initial indications from the tests suggest that the new regulations are having limited effect on curtailing tandem racing.

"It wasn't as big of a change as what I thought it maybe could be," said Kasey Kahne, after completing four laps of pushing Earnhardt and a further three being pushed in return and revealing that it could have gone on longer if they'd wanted.

"I would venture a guess that there will be changes around the corner in one form or fashion," said NASCAR's vice President of competition Robin Pemberton, as it seemed likely that the series will implement still more changes to the size of the restrictor-plate before the Daytona 500. "Today is just the first day of a test," he added.