Cat A COEs are for cars below 1600cc.
Cat B COEs are for cars above 1600cc.
These COEs are non-transferable, meaning, you bid them under your
name and thus cannot be sold.
Open Cat COEs may be used for any class of vehicle.
They are transferable, meaning they can be bought, sold and
transferred freely. So if you are really desperate to get your car
quickly, you can always buy an open cat COE to register your new
car.
Open cat COEs are usually more expensive than
cat A or cat B COEs.
Hmm.. what do you mean by 'import car'?