Car wash killers' appeal dismissed

A couple who shot dead the woman's former lover during an ambush at an Adelaide car wash have had an appeal against their murder convictions dismissed.

Tristan Kay Castle and Jason Bucca were found guilty by a jury of the murder of Adrian MacDonald at Adelaide's Big Bucket Car Wash in 2013.

They are serving 20 and 24-year non-parole periods respectively for the crime.

But the pair argued the trial judge misdirected the jury and admitted invalid evidence, while Castle also said the jury's verdict was unreasonable.

On Thursday, the South Australian Court of Criminal Appeal dismissed the appeal on all grounds.

The pair were tried twice for the crime, with their first convictions overturned by the High Court because of a "substantial miscarriage of justice".

The appeal was in relation to their second trial.