Which are correct:
1) a smoother driving car
1A) a more smooth driving car
2) a harder hitting boxer
2A) a more hard hitting boxer
3) a finer tuned engine
3A) a more fine tuned engine
4) a worse designed machine
4A) a more badly designed machine
These are obviously noun phrases and not full sentences.
1A) is incorrect.
2) is OK
2A) is incorrect.
3) is incorrect.
3A) A more finely-tuned engine.
4) is awkward but possible. You could say "I have never seen a worse designed machine in my life".
4A) is OK as long as it's a direct comparison with something you have already said is "badly designed". The second thing has to be more "badly designed" than the first.
It would have been much easier for us to comment if you had put these phrases into full sentences so that we could see if you could use them correctly in the relevant context.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.