The country's largest car dealer is warning people looking to purchase a second-hand vehicle to check carefully that it has not been damaged by the recent floods.

Hundreds of vehicles were left unusable after being submerged during Cyclone Gabrielle and the Auckland Anniversary Weekend floods.

On websites like Trade Me, there was no shortage of flood-damaged vehicles for sale, including a Ferrari, a Porsche and several late-model Teslas.

Turners Auto Retail Division chief executive Greg Hedgepeth told First Up the company has partnered with insurers and salvage businesses to de-register flood-damaged vehicles and sell them for parts.

"They're then flagged in the system as a flood-damaged car so they will not be going back on the road," says Hedgepeth.

He warns people buying a vehicle privately will not have recourse should they only discover the flood damage after purchasing it.

"I'm sure there's some people out there that might try and ... get it all dried up and get it looking a bit better and then see if they can get some money out of it. So those are the ones that we are very, very aware of. And I think the New Zealand public needs to be aware of it, too."

Hedgepeth says it did not matter whether a vehicle was electric or has a combustion engine, all modern cars have wiring and sensors that are sensitive to water damage.

"It might not be an immediate problem - it might dry out and might be okay for a while - but chances are down the track things are going to start to go wrong with that with that vehicle.

"I would argue that right now if you spot a very good deal in Auckland or Hawke's Bay on a used vehicle, there's a high likelihood that there may be an issue with that car."

-RNZ.