Elliot collected miniature toy cars he wants to fill 4 display cases each display case holds 15 cars he has 28 cars now and he is able to buy 3 more every month with the money he saves from his allowance how many more months will it be until Eliot has enough cars to fill all 4 display cases?
Elliot needs 4 display cases * 15 cars/display case = <<4*15=60>>60 cars
Elliot currently has 60 cars - 28 cars = <<60-28=32>>32 cars to go
Elliot will need to save for 32 cars / 3 cars/month = <<32/3=10.6667>>10.67 months
Since we cannot have a fraction of a month, it will take Elliot 11 months to have enough cars. Answer: \boxed{11}.