Labour is breaking its promise to not introduce new taxes by slapping new taxes on tradies, farmers and large families, ACT Leader David Seymour says.

The "feebate" scheme ignored the fact that vehicles were already taxed and subsidised through the Emissions Trading Scheme (ETS), Seymour said in a statement.

"Let's be clear – this is a new tax. A tradie or a farmer purchasing a Toyota Hilux will be slapped with a new tax of $2900. A family buying a Kia Sportage will be taxed $1230."

The combination of feebate plus ETS charges meant a double tax for Kiwis who needed larger, less fuel-efficient vehicles, Seymour said.

"Motorists pay 77.3c a litre in petrol taxes, plus an ETS tax of 9c a litre. In Auckland, there's a further 10c regional fuel tax. GST is charged on top, taking total tax to around 99.3c a litre (and 110.8c in Auckland). That means EV owners get a subsidy of at least 99.3c a litre in taxes."

The subsidy for EVs was already large over the lifetime of a vehicle, Seymour said.

"The driver of a Toyota Corolla that travels 200,000km at 8L/100km will pay approximately $15,888 of fuel tax over its lifetime (99.3c/L x 8L/100km x 200,000km)."

Listen to Jamie Mackay interview David Seymour on The Country below:

Seymour also believed shifting to an EV would not actually reduce total emissions, because they would not use carbon credits under the ETS.

"They actually free up credits for someone else to use. This is because the total number of credits available is capped under the ETS."

Seymour said the Green Party should ask why it was prepared to tax people who drove cheap, reliable cars, "just so the well-off environmental wing can buy a Tesla."

"The Government needs to drop its ad hoc bans, regulation, taxes and subsidies in tackling climate change. The ETS is the most cost-effective tool we have for reducing emissions."