play up

Never Let Me Goも最後に近くなってきました。今日取り上げるのは誰でも知っている単語ですが、次ぎの文での意味はどうも私の知らない意味のようです。
We deserved a bit of luck by then, because the day hadn't been going at all well. The car had played up on the journey out and we were an hour late for Tommy's test. Then a mix-up at the clinic had meant Tommy having to re-do three of the tests.
二つ目の文の "play up" の意味がさっぱり見当がつかないので辞書を見ます。
・Macmillan Dictionary: to cause difficulties or pain for someone: The printer’s playing up again.; My back’s been playing me up all day.
・Collins English Dictionary: informal ( Brit ) ( intr ) (of a machine, car, etc) to function erratically: the car is playing up again
"play up" にこんな意味があるのですか。　英国英語とありますが、米国人にも通じるのでしょうか？ 上の引用文より３０ページ程後にまた "play up" が次ぎのように出て来ました。
I've known donors to react in all sorts of ways to their fourth donation. Some want to talk about it all the time, endlessly and pointlessly. Others will only joke about it, while others refuse to discuss it at all. And then there's this odd tendency among donors to treat a fourth donation as something worthy of congratulations. A donor 'on a fourth', even one who's been pretty unpopular up till then, is treated with special respect. Even the doctors and nurses play up to this: a donor on a fourth will go in for a check and be greeted by whitecoats smiling and shaking their hand.
この "play up" は先程調べた意味では通じません。　そこでまた辞書を引き直します。
・Macmillan Dictionary: to try to persuade people to believe that something is more important than it is: The newspapers have really played up the low voter turnout.
・Collins English Dictionary: to emphasize or highlight: to play up one's best features
確かに前に出てきた "play up" とは全く違う意味で使われていますね。英語は難しい。