"It's a chance of the lifetime, even at my age you want to race against the best guys in the world," says Bunyan.
"I've got no confidence issues in my riding ability. Most important is getting the right set-up and gear ratio for the track and then get on and go as fast as you can."
Bunyan trailed the field in four of his five races last year but did manage one third, much to the home crowd's delight.
Like any Kiwi track athlete pulling on the black singlet, Bunyan races in the shadow of an incredible legacy. Barry Briggs, Ronnie Moore and Ivan Mauger won 12 world titles between them from the 1950s to the 1970s and New Zealand still ranks second in terms of total titles.
Bunyan races in Britain from March to October but has spent the past 11 summers in New Zealand. As well as racing, he promotes local events and runs training schools, hoping to inspire the next generation.
"My goal is to put New Zealand back on the map with some young riders," says Bunyan. "There is no reason, with the purpose-built bike tracks and some good equipment you can't put good riders out there again."
Safety-conscious Bunyan will tonight be wearing an "air jacket" - a garment that uses technology similar to that of a car's air bag and inflates if the rider leaves his bike, reducing the impact of high speed crashes.
Used widely in equestrian sports - Zara Phillips wore one at last year's London Olympics, where she won a silver medal - the jacket gives protection to the neck and upper body.
It is attached to the bike by a lanyard and triggers when the rider comes off, inflating in less than 100 milliseconds.
"I've had 25 crashes this year so I know it works," he said. "One night I used three air (CO2) canisters at one meeting. It doesn't make you invincible - you still need to use your head - but does give four inches of comfort when you are coming down."
It is not yet in widespread use at grand prix level, but it has been adopted by some riders in Europe.
"I think my air jacket saved me from a lot of damage," said former Danish under-21 champion Patrick Houggard after a particularly nasty crash last year. "I only broke my hand, nose and cut my knee. My gloves, helmet and knee brace were broken but I didn't even have a black mark on my upper body."
It is difficult to make forecasts about tonight's event. Speedway is incredibly competitive - there were nine different winners in the 12 grand prix events last year - and the 413m Western Springs track (with Gothenburg the longest on the circuit) adds to the unpredictability.
For the first time the top four ranked riders - Chris Holder (Australia) Nicki Pedersen (Denmark), Greg Hancock (USA) and Tomasz Gollob (Poland) - are all current or former world champions. Darcy Ward (Australia) and Antonio Lindback (Sweden) are among the dark horses.
New Zealand's Legacy: The Champions
* Ronnie Moore 1954, 1959
* Barry Briggs 1957, 1958, 1964, 1966
* Ivan Mauger 1968, 1969, 1970, 1972, 1977, 1979
* Moore and Briggs also finished second on three other occasions while Mauger was runner up in 1971, 1973 and 1974.
