Concern is growing that the new generation of World Rally Cars for 2017 could be both too fast and provide an inadequate spectacle.
World Rally Championship stage records are expected to tumble next season when the new cars emerge.
More powerful engines, the return of a centre differential to make the cars more efficient and greater downforce generated from increased aerodynamics should make the 2017 machines the fastest rally cars ever.
Drivers have expressed concern about the safety implications of the potential speed increases, but also the possibility that cars will appear to be on rails and less spectacular to watch.
One frontrunning driver who preferred not to be named told Autosport: "In places like Finland, the speeds could be a lot higher. We could be cutting half a minute off some stage records.
"We have to think about what we're going to be doing here. There are places on last year's [Finland] route where you really wouldn't want to be going much quicker."
A senior WRC official admitted rally organisers were unhappy.
"Average speeds in stages are under consideration at the moment," said the source, "so there's a little bit of frustration from some [event] organisers at the teams being given a free hand to make the cars quite a lot faster."
Volkswagen driver Jari-Matti Latvala said his worry was that the cars would look easy to drive.
"I like the power, that is a good thing," he said.
"The one thing I am a little bit afraid for is that the aerodynamics will give the car so much more grip - especially on Tarmac.
"From the outside, this could make the car look a little bit less spectacular; the cars are not going to be more spectacular when they are sitting down even more on the ground."
VW has been running a 2017 mule car since last August, with two-time WRC champion Marcus Gronholm doing much of the driving.
"The car is fast and it feels really nice," Gronholm told Autosport.
"On the tarmac, I was pushing hard and making some fast times on the test stage, but when I came out of the car somebody was asking me: 'Hey, is your grandmother driving?'
"Maybe the cars could be too efficient? I don't know."
See this week's issue of our sister publication Motorsport News - in shops now - for a full analysis of the 2017 WRC concerns and how next year's cars would compare to Group B pace