UPDATED 6.41pm: The focus of Mark Lundy's murder retrial has moved on to whether or not petrol could be stolen from his car.

The Crown alleges a discrepancy in how much petrol was in Lundy's car - is because he drove from Petone to Palmerston North to commit the killings, then returned to Petone.

Detective Nigel Withell says in 2001 he took the car Lundy had been driving to see if he could siphon petrol from it.

"Due to at least two bends in the filler tube going into the petrol tank, it was very difficult to insert the hose."

Nigel Withell says he had to break a spring loaded flap to siphon petrol from the car.

He admitted under cross examination he only tried a 12 millimetre hose, and not a six millimetre hose.

Danny Johansen, who was a detective when he drove between Palmerston North and Petone, told the court he drove the route - and included visiting business Lundy went to - heading north along State Highway 1 towards Levin, turning off and going through Shannon, then heading to Palmerston North.

"I did another trip to the Foreshore Motor Lodge in Petone."

Johansen says all up the journey was 330 kilometres, and he had visited Lundy's business associates, in 2000.

Defence lawyer Julie-Anne Kincade asked Johansen if 76 litres was used to do the entire round trip.

"I'd say I put that total in the vehicle to replace what had been used," he told the court.

"And the car you were driving had a sixty eight litre tank?"

"The specification says so, yes." 

Glen Smelt has experience working with Ford dealerships in New Zealand and Australia.

Using a brochure printed in 1996, he's explained how much petrol a well-serviced Ford Fairmont would use.

"A city cycle was thirteen litres per hundred and highway was eight litres per hundred kilometres," he said.

Smelt says the condition of the road, the driver, and other factors can all affect how much fuel a car uses.

Missing box

Jurors have heard details of a jewellery box not seen since the Lundy double murders.

A statement given to police by Mark Lundy, reporting the theft of the jewellery box, has been read at Lundy's retrial.

Danny Johansen worked on the original murder investigation in 2000, and read the statement taken from Lundy after he went through his home following the murders.

"As I got to the bedroom that Christine and I shared, I noticed jewlery box missing from the chest of drawers next to the doorway," it read. 

Phone records analysed

Phone records show Mark Lundy tried to call his wife at least six times, the morning she was found dead.

Jurors at his retrial have heard a break-down of the phone calls Lundy made the day before, and of, the murders of his wife and daughter.

He was in Wellington for work at the time.

Detective Andrew Buchanan has been asked by prosecution about phone records he helped put together.

"11.04pm - from Mr Lundy's cellphone to the deceased Christine Lundy's cellphone."

"Yes."

Call 73 - 1.05am, the Lundy cellphone to Marcus."

"Yes."

Failing to reach his wife, Lundy then tried close friends.