A convicted murderer's application to appeal his conviction for killing two people, by driving his car into a crowd in Auckland, has been dismissed by the Supreme Court.

Darin Joseph Gardner was jailed in November 2007, after being found guilty by a jury for the October 2006 murders of Kane Wright, 19, and Melissa Viall, 23, with his car on Pakuranga Highway in southeast Auckland.

Gardner said he was trying to help his friend Anton De Graaff, who was involved in a brawl , by causing a "distraction".

The first time he drove into the crowd, he hit Mr Wright , a blow which eventually killed him. He then turned 180 degrees and drove back into the group, instantly killing Ms Viall, who was trying to help Mr Wright.

Gardner was jailed for life with a non-parole period of 18-1/2 years.

Gardner perviously appealed his conviction for the murders in the High Court in Auckland in 2008 and the Court of Appeal in April.