Drivers unconvinced: Mixed response to Formula One's Virtual Safety Car trial at United States Grand Prix

In an effort to improve safety during caution periods of F1 races, following Jules Bianchi's life-threatening crash in Japan last month, the sport's governing body - the FIA - trialled a virtual safety car concept at the United States Grand Prix.

The system utilises the dashboard display in the cars, which indicates whether they are driving within the specified 'safe' speed limit - or 'delta time', with visual and audio cues to warn drivers if they are driving too fast.

During Friday's practice sessions, drivers continued for an extra lap after the chequered flag and were required to adhere to the delta time, and although reigning F1 champion Vettel admitted the concept still needs tinkering, he gave it the thumbs up.

"I think I had a short glimpse at the end there. It does what it is supposed to do," the German said in Austin.

"It needs some finetuning but it works."
Bianchi crashed into a tractor that was moving Adrian Sutil's damaged car at Suzuka last month and, while details remain disputed, the FIA insist the French driver did slow down before his accident, although the insinuation of these proposed changes is that he should have slowed more.

While all drivers seem pleased that the FIA has reacted so promptly to Bianchi's accident in an attempt to improve safety and take the decision to slow down out of the hands of the men in the cockpit, Jenson Button remained wary of the initial virtual safety car protocols, after trying them at the Circuit of the Americas.

"There are positives and negatives. When you're wheel-to-wheel and the system comes on you can't just hit the brakes like we are now to get the speed down," Button said.

"In that respect it's very tricky. I like the idea but you do spend a long time looking at your steering wheel."

Romain Grosjean agreed: "It was very, very difficult."

But Pastor Maldonado's response made both Grosjean and Button's complaints seem frivolous, as the Venezuelan declared the process to be "very easy".

"You get a dashboard display that you need to follow if you are plus and you are on the target, or you have a tone in the earpieces if you need to drop a little bit," he said.

"It's very easy. If you are plus it's OK and if you are up you just slow down so it is very easy to manage."

Bianchi remains in a "critical but stable" condition in hospital in Japan, just under four weeks after his accident, where he suffered severe head injuries.