I was in same dilemma in 2018 when i was searching for an auto 1000cc for my sister, my friend got passo then 2015 model, neat and clean 4.5 grade 32k driven. I test drove that and then the cultus
Passo's drive was smoother, interior quality was better, seats more comfortable but more engine noise (i guess due to cvt transmission)
Cultus drive is comparable but minor jerk is felt on gear change, interior quality is not that much inferior, pick is very good, fuel efficiency is same as passo, its brand new, you can shift to manual gear change mode, vibration is more as compared to passo.
Its been 1 yr my friends passo and my cultus are both running fine alhumdulilah.
Conclusion
Both cars are good and both offer almost same comfort
Now it depends on your mindset
If you're prone towards brand new, zero meter , phada free car go for cultus
If you need tech loaded jdm go for passo
If i were in your place , id have gone for cultus eyes closed.
Bht khwari hai achi saaf suthri jdm dhoondna. Mil jae to price kafi zda.
Cultus lene mae ye sakoon hai k khwari ni hti.
Baqi problems to brand new civic mae b nikal atay hain thats mere luck
And jaha tak bat hai apki value for money ki to at the moment koi 1 gari b value for money ni hai( civic grande altis city cultus) kisi gari ki b price justified ni hai.
So just go for cultus as soon as possible.
You never know kab price increase hjaey.
These are my personal views. Others can disagree but i shared to help because i was in same situation 1 yr back and i was more inclined towards passo. My father forced me to get cultus and he was right .
Best of luck