With up to 90,000 people expected on the Weston Park site in Staffordshire, police say congestion is unavoidable.
Only people with tickets are advised to travel to the festival with non-festival traffic urged to stick to main roads and motorways over the weekend.
Drivers from the west should leave the M54 at junction 3, and those from the east should leave the M6 at junction 12 and then use signed routes.
Drop-off and collection points will be signposted from the A5 and shuttle buses will be running from Wolverhampton and Stafford rail stations.
Event commander, Ch Insp Peter Taylor, said: "With up to 35,000 cars expected, some congestion is inevitable. Signs advising motorists to avoid the area around Weston Park during the event are already up."
Meanwhile, Essex police have warned music fans that sniffer dogs will employed to track down and arrest drug users at the southern leg of V Festival.
They hope the drug detection hounds will help prevent festival goers from bringing illegal substances onto the Hylands Park site in Chelmsford.
There will be around 500 police officers on site. Sgt Andy Sawyer, of Essex Police, said: “The possession of cannabis or any other illegal substance is a criminal offence and those people found with such drugs will be liable to arrest, removal from the festival and prosecution.
“We just want everyone to have fun, enjoy the music and not to miss out on the entertainment because they have been arrested.”
The dogs are passive drug detectors, which means that if they smell traces on anyone they will quietly sit down next to them.
So if you're off your nut and see a cute doggy from afar, it's probably best not to go and stroke it. You have been warned!
The sold-out V Festival takes place this weekend (19-20 August) at Hylands Park, Essex, and Weston Park, Staffs.
Radiohead, Kasabian, Morrissey, Razorlight, Faithless and Beck are among the many acts on show. Click here for more info.