It follows opposition to the proposed fees from the Guernsey Motor Trades Association (GMTA).
The proposals are aimed at cutting the number of big high emission vehicles on the Channel Island's roads.
The GMTA said it was "horrified" at the initial proposals which would see the price of cars measuring more than 1,901mm-wide increase by Â£2,400.
President Dave Beausire said after a meeting with the Environment Department: "The meeting was very calm and professional.
"We have put our points across and we will wait for the amendments to come out before commenting further."
Revised width and emissions tax proposals will be published before the end of the year, says Guernsey States.