The parents of a 6-month-old baby killed in an Easter car crash did not know she had died until they began recovering in hospital.

A suspected drink-driver led police on a 100km chase along highways north of Auckland - as he weaved through traffic at speeds up to 170km/h.

A line of congestion 10km long north of Auckland and delays of up to 90 minutes elsewhere have hit NZ highways as traffic continues to build.

An elderly driver who caused a "horrendous" multiple-vehicle smash on Auckland's Southern Motorway has received a six-month driving ban and a $1000 reparation order.