"It is not acceptable that businesses that rely on fuel such as commercial vessels, market gardeners, subdivision and roading developers do not know yet if they qualify for an 'off road' rebate for the tax or how they may process it," he said.
Bodger also suggested that the new legislation might run into problems down the line.
"Unfortunately this could be a mess that business must tidy up following the hurried legislation.
"My concern is that business will have to wear a major cost increase until matters are rectified. Uncertainty and greater costs could potentially be passed on to consumers, which is not a great state of affairs."
Tips for reducing fuel consumption:
1. Make sure your tyres are pumped correctly
The Automobile Association (AA) has found incorrect tyre pressure uses nearly 8 per cent more petrol than having them pumped the correct amount.
2. Try to avoid rush hour
Idling for long periods and constant stopping and starting uses more fuel than a smooth run from A to B. The AA says turning your engine off if you're stuck in traffic for longer than 30 seconds is better than keeping the car running, and the MTA recommends planning ahead to run errands during off-peak times.
3. Don't speed
According to the MTA, fuel consumption increases by about 6 per cent for every 10km/h faster you go over 90km/h. For most drivers, 100km/h is a good compromise between travel time and fuel economy.
4. Keep your load light
A bag of golf clubs in the boot or a pair of bikes making an unnecessary trip to the supermarket on the roof rack mean more petrol is needed to propel your car around, the AA says. Reduce your load and only take what you need with you.
5. Use your aircon - but only for a little bit
It seems counterintuitive, but opening your windows to cool the car down is actually less fuel efficient than using the air conditioning because it creates drag, the AA says. However, blasting the A/C or leaving the back window demister on after they've done their job is an unnecessary drain on fuel.
6. Take care of your car
Regular services and tune-ups could reduce your fuel consumption by up to 4 per cent, the MTA says. The AA puts the numbers even higher, saying a well-maintained car can use 10 to 20 per cent less fuel than one that's badly looked after.
7. Drive smoothly
Don't accelerate aggressively, as this uses more fuel than necessary. Smooth starts and stops help conserve petrol.
8. The simplest way to cut down on petrol costs is to drive less
Short trips to the dairy don't need to be done in the car, and the AA estimates a third of trips in New Zealand are less than 2km long.