Working with children at various stages of early development, I have sometimes heard the following from parents:
"I talk to him like he's an adult... I want him to have a good vocabulary..."
As parents we all want to teach our children as much as we can and give them the best start. However, when they have difficulties in learning language, and/or additional learning needs, we need to adapt what we are doing by slowing things down and by giving them a reason to communicate.
First; stop what you are doing, then; stop yourself responding to your child straight away. Count to 3, or 5! This bit is actually really hard, I've tried it myself. Especially when you've got other little ones running about and interrupting...
Spending time with your littlies makes you finely tuned to their every need and desire, often before they even realise it! So next time you are about to give little Johnny the car that's out of reach, just stop for a few seconds...
Watch what he does when you don't just pass that car to him. Does he look puzzled that his car hasn't magically appeared in his hand? Does he make a teenage-like grunt and point to what he wants? Does he actually change his mind and decide he'd like the crayons that are next to the car instead?
By watching, we can see exactly what the child is interested in and then we can...
Little Johnny may have had the ability to try to say "car" for a while, but not had the opportunity to practice. As the saying goes, practice makes perfect. So, if the first time he says "uh" the next time he might say "ar" and the next time "tar", until he finds a word that you can consistently recognise as "car".
Once you can give your child the time and opportunities to talk, and they realise there is a benefit to talking (I.e. things will happen for them much faster), there should be no stopping them... In my experience, this is the breakthrough moment for children with any number of abilities or disabilities, and can be quite amazing to see the difference in a child who can suddenly make their needs known!
ON YOUR WAY
Well done! For being patient, and not jumping in, and giving him the opportunity to try! It's really hard to do, especially if he has other siblings (I'm talking from experience! ) but it's not impossible, and it certainly is very rewarding to watch your child's confidence in communication developing.