The 26-year-old Canberra festival yesterday announced that car care brands distributor MotorActive had signed off on a six-year sponsorship renewal after 20 years' involvement with the Australian car festival.

The sponsorship agreement covers their brand Liqui-Moly, who are the naming rights sponsor for the National Burnout Masters - one of the largest burnout competitions in the world.

MotorActive founder Bruce Morrison said his company had worked hard with the new Summernats owners to clean up the perception of burnouts and legitimise it as a form of professional motor sport.

"Almost immediately after we formed the National Burnout Masters, a number of smaller feeder events started to appear across the country, all occurring on designated burnout facilities," Mr Morrison said.

"This meant that videos rapidly started to appear on YouTube with footage of cars doing burnouts in safe, controlled environments on the track, instead of in dead end streets."

The Summernats festival entered its final day yesterday, with reports of relatively good crowd behaviour.

The event came close to folding following bad crowd behaviour in 2008 after patrons were kicked out for misbehaving and a 300-strong mob marched around the venue in retaliation yelling "show us your tits".

An ACT Policing spokesman yesterday said despite numerous intoxicated patrons, they had made no arrests at the showground this year.

However, he said police were still investigating whether some incidents outside the event were related to Summernats.AAP