a narrow road where two cars can't pass by each other
a road that's so narrow two cars can't get by each other
この場合、次のように表現できるかと思います。
ーa narrow road where two cars can't pass by each other
「２台の車が互いに通り過ぎれない狭い道」
to pass by で「通り過ぎる」
ーa road that's so narrow two cars can't get by each other
「狭すぎて２台の車が互いに通り抜けれない道」
to get by で「通り抜ける」
例：
The road in front of our house is so narrow two cars can't pass by each other at the same time.
「家の前の道はとても狭くて２台の車が同時にすれ違うことができない」
ご参考まで！
カナダ 
