The Early Turnover Scheme (ETS) is an incentive to encourage vehicle owners to replace their diesel vehicles with more eco-friendly vehicles like hybrid-electric vehicles.
To qualify for ETS, the vehicles owner have to deregister his/her existing vehicle, and within one month, replace it with another eligible eco-friendly vehicle. He/she does not need to bid for COE for the new vehicle and instead, gets to enjoy a discounted Prevailing Quota Premium (PQP).
Important thing to note is that the bonus is pro-rated, proportionate to the number of remaining COE that is unused. Basically, the earlier you replace your vehicle, the more COE is unused, and you get to enjoy a bigger discounted PQP when you purchase your new vehicle.
You can check out the full details here: https://www.onemotoring.com.sg/content/onemotoring/en/lta_information_guidelines/buy_a_new_vehicle/Early_Turnover_Scheme_For_Category_C_Vehicles.html