Fortunate to have both cars.
Cerato has better interior fit and finish then Suprima. Cerato is for people who like to travel in comfort and win for rear passengers. FC town driving better than Suprima. Outstation about the same. I believe Cerato now comes with 7" screen. Mine still the 4.3". Also the Cerato I bought comes with 3 year free service/oil thingy. SS only now have. My SS does not have that free 3 year service.
Suprima is for people who want to get there fast. Rear passengers will suffer

The 1.8l Cerato is hopeless between 80km-120 km on B-roads (non-highway roads). Hopeless because the max torque at about 5k RPM. There is no way to overtake quickly in the Cerato. You need a huge distance to overtake cause you need to rev the engine to get to 5k RPM. Then when you do get that 5K RPM, your overtaking chances are gone. To make matters worse, the EPS is dull. No road feel. I wasted 30 mins total driving time unable to overtake which is annoying. Arriving 10 mins late (reported by waze is annoying especially since I claw back 30mins with same route using the SS). The turbo in SS is intoxicating. Even better since it comes at 2k RPM and stays there until 4k RPM before dropping a little. Max torque gives you lots of overtaking opportunities with lots of power to spare.
Which am I more satisfied with:
Daily commute-including jams: Cerato or SS. Makes little difference. Rear passengers will prefer Cerato
Outstation driving: SS
Which one more beautiful: SS>Cerato. Particularly rims. The Cerato front end tries to hard at imitating BMWs.
Rear end Cerato is better.
Interior HU: Cerato better. Actually Cerato has different layer bits, but the bits which you touch are the soft touch bits. SS has a good soft touch dashboard, but no use since my hand is not going to touch all the way to the screen. Cerato has better soft touch management. Though one part I hate about the Cerato is the steering wheel. Too big, too hard and the stitching at the lower left and right corners hurts my hands if I grasp tightly especially during cruising. SS steering is miles better.
Coldest AC: SS is way cooler than Cerato. Cerato is better at temp management. SS seems to think the entire car needs to be the level you set before slowing down the AC. Cold AC is fine with me.
Aside from that I believe Cerato is better than Suprima. It is worth the price difference. Just don't buy it if you like to drive. If you stay at highway place all the time town driving, then it is a good choice. However, since the SS is RM20k cheaper but has slightly worse FC, I got extra 20k of fuel income to play with compared to the Cerato. I'm reserving part of that 20k to upgrade better HU and converting the rear end to twin exhaust...if R3 will come out a kit about it.
Very well written.