Mr Martin said the driver regained consciousness before his trip to hospital.
A Targa media spokesman said the pair were experienced Targa competitors. They were running fifth overall in the two-day Targa Regional Rally when the accident occurred.
A second accident in the same stage did not injure driver Mark Hellier or co-driver Glenn Edley from Auckland but Mr Hellier's Porsche 911 was badly damaged.
Geoff Laurent from Cambridge said he was "thoroughly" enjoying Hawke's Bay in his turbocharged Subaru WRX, if a little torn.
"The scenery is so beautiful but I have to keep my eye on the road as well," he said.
With speeds up to 200km/h for the competitive class it is far from a jaunt in the country.
Auckland's Alasdair Patrick said it was "a bit of both" from his open-top Aston Martin.
In an orange Ford Mustang, rally goodwill ambassador Ray Williams took Napier MP Stuart Nash and Tukituki MP Craig Foss for a ride.
When not ferrying parliamentarians Mr Williams, the holder of the New Zealand road car land speed record of 317km/h, handed out sweets to children.
"I'm a Jaffa handing out Jaffas in a Jaffa car," he said.
Event director Peter Martin said it was "an excuse for people interested in cars to socialise".