Jenson Button believes this year's Formula One cars won't be much faster than the ones used in the GP2 series.
Under the new aerodynamic regulations, there is a large reduction in the amount of downforce the cars generate, which results in a loss of speed in most corners.
Although most drivers were impressed with the cars' torque during last week's test session in Jerez, the lap times were significantly slower than the tests at the same track last year.
The fastest time of the four-day test was set by McLaren rookie Kevin Magnussen, who was almost six seconds slower than the fastest times in Jerez last winter, but some drivers were another four seconds slower than the Dane.
Since the GP2 series wasn't forced into the same technical changes, Button believes the cars competing in the support series will run their F1 counterparts close.
"They will be a lot closer on certain circuits," Button noted.
"We'll be quicker, but not that much quicker.
"By the end of the year we might not be that far off (2013 pace), maybe a couple of seconds, which will be pretty good when we get a real handle on where we are."
Button noted that the new, harder Pirelli tyres might have a bearing on the relatively slow lap times at the Andalucian track.
"We think they are half a second slower," the 2009 World Champion added.
"The cars are also heavier, about one to 1.2 seconds through weight, so that's 1.6, 1.8 seconds already from those two changes."
Any reproduction, publication or redistribution of this material without the written agreement of 365 Media Group is strictly forbidden.