What are cars called that look stock but have lots of performance modifications in Japan? Americans call them Sleepers.

1 Answer 1


チューニングカー (from "tuning car") or チューンドカー (from "tuned car").

From JMdict / EDICT (edict2u) dictionary:

チューニングカー;チューンドカー /(n) tuned car/modified car/EntL2831780/

  • 1
    This would be the closest, but it's worth noting that チューニングカー doesn't convey the meaning of the "look stock" part. It just refers to cars with performance modifications, with or without exterior changes.
    – naruto
    Jul 27, 2023 at 14:35
  • Dictionary does not have any other entries for such cars...
    – Arfrever
    Jul 27, 2023 at 16:11
  • 2
    You might be correct. However, if emphasizing the "look stock" aspect is vital, we can employ a similar approach as used when translating "weeaboo". You could use スリーパー and then provide an explanation of its intended meaning (either in parentheses or in a separate sentence).
    – naruto
    Jul 27, 2023 at 17:04
  • @naruto What about 普通外観のチューンドカー? Normal meaning of "sleeper" is "person who sleeps", and I would dislike adapting some rare slang meaning.
    – Arfrever
    Jul 27, 2023 at 18:34
  • 3
    Yes something like 普通の外観のチューンドカー and ノーマルな外観のチューンアップカー is short enough and descriptive enough at the same time (see this as for why it's better to keep の). I'm not a car fan, but I found this definition of sleeper is already in ALC, Wikipedia, and so on, so it probably doesn't to have to be dismissed as "some rare slang".
    – naruto
    Jul 28, 2023 at 5:58

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