The Government's currently exploring how it could rejig its Clean Car Discount scheme.
Usually, there's no such thing as a too-successful policy, but the Clean Car Discount scheme is supposed to be revenue neutral.
The fees charged on heavy emitters, otherwise known as the 'ute tax', are supposed to pay for all the discounts on clean cars.
But demand for low-emission vehicles has well outstripped the fees collected, so the Government is having to rethink it.
It's expected to make announcements about that in the coming weeks.
Newshub understands hiking the tax on high emitters is not a realistic option so the Government's going to have to decrease demand.
Currently, the discount is available at varying rates to EVs, Hybrids and low-emitting petrol vehicles.
It's understood one option being considered is changing the eligibility. We're told it won't immediately move to EVs only.
But the Government could, for instance, remove the low emitting petrol vehicles like Swifts from the discount scheme to make it more sustainable.