Question: Do I say a beracha when I check my car for chametz? Does it matter when I check it?
Answer: The Rema (OC 433:13) writes that one should properly clean every room of their house before they do bedikas chametz. This applies to any room where one may have taken chametz into throughout the year. One must, therefore, clean one’s car before Pesach.
The Chayei Adam (119:18) writes that even though one needs to check one’s pockets and containers, the main mitzva of bedikas chametz is specifically to check their house. One would, therefore, only recite a beracha upon checking their house. There is a discussion, however, whether one should recite a beracha upon checking their car.
R’ Ovadia Yosef (Yechave Daas 1:5) writes that one should do bedikas chametz in one’s car after they’ve looked around their house the night before Pesach. One should not repeat the beracha even if it took a while to get to one’s car. R’ Shlomo Zalman Auerbach (Halichos Shlomo, Pesach 5:5) adds that if one can’t do it that night, one should do so earlier during the day. Regardless, as it isn’t one’s house, one would not say a beracha.
R’ Ben Tzion Abba Shaul (Ohr Letzion 3:7:9; 19) writes however, that if one only has a car then one should say a beracha upon doing bedikas chametz on it. Similarly, R’ Moshe Feinstein (Mesores Moshe 1:286; 2:185) questioned whether a car is considered to be more like a house. If one only had a car then one should recite a beracha on searching it for chametz (See Rivevos Ephraim 4:106).
In conclusion, one should clean one’s car well before the night of bedikas chametz. One should begin bedikas chametz on their house before searching their car. If one only has a car then they could say a beracha before performing bedikas chametz. Otherwise, one wouldn’t say a separate beracha.