1.
If you smash something up, you completely destroy it by hitting it and breaking it into many pieces.
She took revenge on her ex-boyfriend by smashing up his home...
You could smash the drawer up with a hammer...
PHRASAL VERB: V P n (not pron), V n P
2.
If you ~ your car, you damage it by crashing it into something.
All you told me was that he’d smashed up yet another car.
PHRASAL VERB: V P n (not pron)