Leading Formula 1 drivers say the need to preserve the new-for-2011 Pirelli tyres will totally change the way they go racing - though Mark Webber has warned that judgement should be withheld until they are tried in race conditions.
Pirelli has responded to calls for higher tyre-wear rates and deliberately designed rubber that will not be capable of lasting as long as the 2010 Bridgestones. The aim is to create more exciting grands prix both by prompting extra pitstops and creating a situation where drivers will be running at different pace depending on how they are handling their tyres.
McLaren's Lewis Hamilton said he was not enjoying having to nurse the tyres.
"It's very strange. Even [compared to] last year when we had heavy fuel and you had to drive it a little bit easier at the beginning of the race to preserve the tyres," he said.
"Today I probably drove a little bit easier on the first long run, but the tyres just go away so fast and there's nothing you can do about it.
"The second run I tried to look after it even more and it was like driving an out-lap, very slow and not particularly exciting. It lasted a little bit longer but it didn't feel like I was really racing the car."
He feels the tyre strategy is making driving less of a challenge.
"On these tyres you have to drive very slow and it's not very physical at the moment," said Hamilton. "I did 90 laps today and I feel like I could start all over again, it was that easy to drive."
Hamilton suggested that it was also harder to judge the new McLaren's true performance because the team could not tell whether issues were car or tyre-related.
"It feels difficult to know how much of it is car and how much is tyres," he said after today's Barcelona test session. "The tyres are very difficult to use this year, and when you come here even more hardcore than it was in the last two tests we had."
Red Bull's Webber is convinced that the new tyre philosophy will mean more overtaking, though he suspects performance disparities will be so big that passing moves could become too easy.
"I think there will be more overtaking," he said. "It's easier for us to look average. You're even talking to yourself in the cockpit 'come on Mark, that was messy, that was scrappy', it's very easy to be losing time when the tyre goes away a little bit, so you've got to have that in mind.
"If that was in a race situation and someone was on a different strategy then we might have some racing, but the only thing we've got to keep an eye on, unfortunately, is that we're going to have such a big difference in speed that if someone is doing something different and you're trying to go longer or whatever, it won't be a fight, you'll just go straight through and disappear.
"So that's the only thing, there's such an extreme difference in pace that there will be some overtaking but I don't know how spectacular it will be."
He added that the drivers' current feelings about the tyres could be proved totally wrong once the season got underway.
"This has happened in the past. Last year at Jerez we were completely s**tting ourselves with the Bridgestones doing long runs, thinking 'oh my God, we're going to be stopping every...' you know, then we get to the first races and drive around all day [on one set]," said Webber. "We need to go racing."
The teams have had their first chance to try Pirelli's intermediates and wets properly at Catalunya this week, with both this morning and the early part of Friday's test taking place on a damp track.
Force India's Adrian Sutil said his first impression of Pirelli's rain tyres was not positive.
"It's very different. Pirelli is not good in the rain," he said. "The tyres are not lasting long and it's just very slow compared to Bridgestone.
"But we did some running, it was very bad at the beginning, we did a few changes and at least we got it under control in the end and it was a pretty decent run. But performance-wise it was quite far off what I'm used to.
"But that's how it is. The tyres are very different to last year. It's a new challenge, it's not a bad thing."
Webber said the intermediates were very durable, though when asked if he felt they were 'good', he replied: "not bad."
The Australian added: "You get bang for your buck. You buy a set and they last a while. I did a lot of laps on mine, I had one set all morning, so 43 laps."