Translation guide
A car that has been altered from its factory specifications, often for performance or aesthetic reasons.
The broad concept of a car that has been modified in any way.
General term for a modified car. Neutral and widely understood.
彼は改造車を何台も持っている。
He owns several modified cars.
Loanword from English 'custom car'. Often implies aesthetic or personalization modifications.
カスタムカーの展示会に行った。
I went to a custom car show.
Specifically a car modified for performance, especially engine tuning. Common in car enthusiast circles.
彼のチューニングカーは300馬力出る。
His tuned car puts out 300 horsepower.
A car modified primarily for appearance, such as body kits, paint, or stance.
Car modified for visual appeal, like body kits, wheels, and interior styling.
ドレスアップカーのコンテストで優勝した。
He won the dress-up car contest.
Can also refer to visually modified cars, but is broader.
あの改造車は派手なエアロパーツをつけている。
That modified car has flashy aero parts.
A car modified for increased speed, handling, or power.
Standard term for a performance-tuned car.
サーキットでチューニングカーを走らせるのが趣味です。
My hobby is driving tuned cars on the circuit.
Also used for performance modifications, but less specific.
改造車でドラッグレースに出る。
I enter drag races with my modified car.
A car modified in ways that violate vehicle regulations.
Specifically a car with illegal modifications. Used in legal contexts.
不正改造車の取り締まりが強化された。
Crackdowns on illegally modified cars have been strengthened.
Another term for illegally modified car, slightly more direct.
違法改造車は車検に通らない。
Illegally modified cars won't pass inspection.
改造車 is the broadest term for any modified car. カスタムカー emphasizes visual customization, while チューニングカー focuses on performance tuning. Use 改造車 when unsure.
The direct translation 'modified car' is not commonly used in Japanese. Instead, use the specific terms above depending on context.