Most CVTs suffer from what is called a ‘rubber-band’ effect, where the engine revs rise higher than the speed, which makes the engine sound like it's straining. Honda’s CVT automatic transmission in the City is a belt-driven system and is known to be a bit noisy under hard acceleration, partly because the noise insulation in the Honda City isn’t very good. To be honest, there is not much you can do except drive with a light foot and don’t floor the accelerator to keep the revs down.