Red Bull's Horner says one-stop grands prix bad for Formula 1

Horner's remarks follow an uneventful Canadian GP in which the majority made just one stop for new Pirelli rubber.

"One-stop races aren't good for Formula 1," said Horner.

"You need to have two to three stops, and that's important. Unfortunately, the tyres we have now are just a bit too conservative.

"A few years ago we had a bit more downforce that abused the tyres a bit more.

"Pirelli did go too far if you think back to Silverstone 2013 [the British GP that included several tyre failures], but as a result of that their reaction is we have ended up with a pretty conservative tyre.

"The changes over the winter, going into this year, means they've gone a bit more conservative again, whereas the tyres we had last year were about the right balance for strategy and degradation."

Fuel conservation was also a factor in the lack of spectacle in Montreal.

The lack of a safety car, a usual occurrence around the Circuit Gilles Villeneuve, ensured a number of cars were marginal on fuel come the chequered flag.

Horner believes it is time the drivers be allowed to push their car to its limits.

"The other thing not good for Formula 1 is fuel-saving. It should be a sprint race," he said.

"Lift and coast doesn't belong in a sprint race. That's not the message Formula 1 should be putting across.

"I'd either shorten the race by five laps, or whatever, or increase the amount of fuel, but it needs to be a flat-out sprint race from start to finish."

Horner believes armchair viewers will continue to switch off if messages of that nature proliferate races in the future.

"If you are a fan sitting at home watching that, you don't want to hear that," said Horner.

"You want to see the guys going flat-out racing each other, so it's something we need to take on aboard and react to."

Horner has also questioned the legality of such radio messages, in particular as reigning champion Lewis Hamilton was told how far - either 50 metres or 100m - he should lift and coast.

Such coaching instructions are supposedly banned under current FIA rules, yet Mercedes avoided any warning.

Horner said: "It sounds like coaching if they are telling them where to lift and how much to lift. If that's the case we may as well get in and do it."