While other American car owners at the Oamarican car show in Oamaru on Saturday had models of the cars they owned in their back windows, the Mitchells have a papier-mache concrete-filled pink pig.
The number plate on the 1960 Cadillac Series 62 is "60 PIG".
So why the nickname?
"It's the way it looks, and we're going to leave it like that," Mr Mitchell said.
The big-finned long-bonnet Cadillac, with a 390-cubic inch V8 and three-speed auto, still has its original paintwork, although worn in places, and chrome.
Mr Mitchell has installed new upholstery, headlining and carpet on the inside, but has no plans to redo the outside.
Instead, he will move on to "project two", a Pontiac Bonneville bought just a few months ago.
They have had the Cadillac for about a year, buying it from its owner in Invercargill.
Despite its sheer size, and difficulty getting it into a parallel park, the Cadillac gets a lot of use.
It goes out at least twice a week, sometimes just to get the groceries.
Both say it is easy and fun to drive, liking it better than their later and more compact Holden Calais.
"Pig" was on display with other American cars at the Oamaru Showgrounds on Saturday, 75 having registered on Thursday and Friday for the inaugural Oamarican car show.
One of the organisers, Wayne Sinclair, was rapt with the number.
"We were aiming for 70, so we have exceeded that," he said.
Over the next week a debriefing will be held, at which it will be discussed whether to have the event every year or second year.
To reach that decision, they are asking those taking part in the inaugural event.
"Next time it will be easier because we already have a lot of things in place," he said.
Mr Sinclair also expected even more cars, word of mouth about the inaugural event encouraging others to attend.
On Saturday, the cars were lined up for the public at the Show 'n' shine Country Fair, followed by a social and prizegiving that night.
Yesterday, there was a farewell breakfast at the Detroit Diner.
