Convertible – A car with a soft roof that can be folded down or removed
To convert the car is not sensible (convertible) when it rains because when the roof is folded back, the rain gets in.
Examples of convertible in a sentence
She knew he was having a midlife crisis when he bought an incredibly impractical convertible that they really couldn't afford.
The high winds blew the soft roof clean off her brand new convertible.
Despite owning a convertible he'd never driven with the roof down due to the consistently bad weather.