A private post-race test at Circuit of the Americas on Monday gave Maverick Vinales and Aleix Espargaro the chance for a back-to-back comparison between the 2015 and 2016 Suzuki chassis.

Vinales - who claimed his best MotoGP result with fourth in Sunday's race - has favoured the 2015 version since winter testing, with Espargaro reaching the same conclusion by round one in Qatar.

But to Vinales' surprise, the 2016 version felt better on Monday.

"We've been comparing the old chassis with the new one and we are quite surprised, because here looks like the new one was a bit better. So I want to kill myself!" he smiled.

"The first part of the day we didn't ride because the track was incredibly dirty. My first lap was a 2m 8. Incredibly slow. Then the track got better and we were fast, more fast than our pace in the race. Much more fast."

The young Spaniard explained that the 2016 chassis was unchanged from testing and the difference was down to the character of the circuit.

"Phillip Island and Qatar have many fast changes of direction, here there is only one. The rest are quite slow," he said.

"Always I feel so strong in fast corners like Sector 1, but then when it is hard braking like Sectors 3 or 4 I have problems.

"[With the 2016 chassis] the bike stops more and I can turn a little bit better on the hard braking. This was our weak point the whole weekend and with that chassis we improve, so we will consider to try to use in Jerez for sure."

Indeed, Vinales revealed that he now plans to test both versions on the opening day of each future grand prix, to determine which is best for that particular event.

"Yes, I think so," he confirmed, "We need to be quite intelligent on the Fridays and give an opportunity to both chassis."

However Espargaro, who finished 2.3s behind Vinales on Sunday, still preferred the 2015:

"We tried the [2016] frame, exactly the same setting as Qatar and then with something to make the bike more rigid. It was good because it changed a lot, just changing one part we could change the rigidity of the frame. But basically for me the 2015 chassis is better.

"I have better feedback in the turn, they are not so different but in MotoGP today three tenths is enough to stop you going into Qualifying 1. So is good enough to keep working on this one."

Vinales - tipped to replace Jorge Lorenzo should the reigning champion complete an expected move from Yamaha to Ducati for 2017 - is currently eighth in the world championship, having fallen from a podium place in Argentina.

"We know if we work so hard we can one day be on the podium. [Here] I was feeling not really good on the bike and finally we make fourth place. So when I feel good on the bike like Argentina, and don't crash, I can have the podium."

Looking at the upcoming events before the summer break, he added: "For me, Assen can be really good track. Last year I was feeling quite strong there... [a podium at] Assen or Montmelo would be incredible."

The fourth place by Vinales was Suzuki's best result since returning to MotoGP at the start of last season.

By Peter McLaren