BERACHA AHARONA

Question

Dear Rabbi, I have already included the following question, together with some others and am still awaiting an answer. I understand you recieve many posts and will answer them as soon as you can. However, the following question comes up often, so a speedy answer would be most appreciated. My question is: In the case where I forgot to say a beracha aharona, and I have already left the house, can I a. say the blessing in the car? b. how about if I can see into the house or even the place where I actually ate(from the car or outdoors)? thank you so much for all your time and efforts.