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！
a narrow road where two cars can’t pass each other
a narrow road where two cars can’t pass each other
a single-lane road (with no room to pass)
a one-car-wide road
a tight/narrow mountain road with no passing space
「対向車とすれ違えない狭い道」は、英語ではまず “a narrow road” を軸にして、状況を足すのが自然です。
ポイントは「すれ違う」が “pass” になることです。車同士がすれ違う＝two cars pass each other。
なので “a narrow road where two cars can’t pass each other” と言うと、意味が伝わります。
カナダ 
アメリカ合衆国 
