Japanese speakers
Mistake: Pronouncing it as "GURIIN KAA" with a clear gap and a full katakana [a].
Why: Katakana English preserves each word as separate and uses different vowel qualities.
Fix: The n of "green" links directly to the k of "car": [ˈɡriːnˈkɑːr]. In fast speech, the n may assimilate to [ŋ] before the velar k: [ˈɡriːŋˈkɑːr]. Say it as one prosodic unit.
Korean speakers
Mistake: Producing a clear syllable break between "green" and "car" with fresh aspirated [k].
Why: Korean prosody favors clear boundaries and ㅋ carries aspiration.
Fix: Let the n slide into the k with optional [ŋ] assimilation: [ˈɡriːŋˈkɑːr]. The whole thing is one adjective-noun unit.
Spanish speakers
Mistake: Producing the r's as Spanish tapped [ɾ] or trilled [r].
Why: Spanish r is a distinct tap/trill; English r is [ɹ] approximant.
Fix: English r is [ɹ] — no tongue tap: [ˈɡriːnˈkɑːr]. In RP, the final r of "car" may not be pronounced except when a vowel follows in the next phrase.