St John Ambulance is rolling out new yellow vehicles it hopes will improve visibility and safety.
It says yellow is the most noticeable colour on the road, especially in low light, and the most visible for people with colour blindness. The vehicles also have a bolder design that includes more reflective signage.
Two prototypes will be on the road from Friday: one in Auckland, the other in Hamilton.
Operations director Michael Brooke says he expects more people will now notice - and give way to - ambulances. "We travel more than 18 million kilometres a year - probably about 450 times a day we're turning on our lights and sirens and basically combatting the New Zealand roads," he says.
"If we can make our vehicles more obvious to people, then we think we can make them safer, and that's pretty important to us."
Mr Brooke says the entire fleet will be converted to yellow over the next 10 years.