s1: A has a car. s2: B has a car. When you combine both s1 and s2 with 'and', what is the result? A and B have a car or A and B have cars. Pls advise.
If we are restricted to the choice given then
A and B have cars.
If not, then
Both A and B have cars.
The first answer is fine colloquially.
"(Both) A and B have cars." does not make it clear that each one has only one car.
'Both A and B have a car.' and 'A and B both have a car.' are better, but I think that using 'each' is best because 'each' refers to A and B individually while 'both' refers to them together.