Take this route:
Borivali - Goregaon - Arrey Colony - Powai - Mankhurd - Vashi - Panvel
Before you reach Panvel, you'll need to be on NH4 and not take the expressway. The NH4 route will be sticking to the left, at the point where expressway starts. Keep a lookout for road signs. Just below it is a very big circle. Take the most extreme right, which is the Panvel Bypass (which continues towards JNPT, Uran). At the end of that road is a T junction, where right is Uran, left is NH4/Pune. Take a left.
Then, Panvel - Khopoli
After Khopoli, half the ghat ascent is on a one-way 2 lane road. After this, the road you are on (Nh4) joins the expressway, so, part of khandala ghat climb with be on the expressway (bikes are allowed here and its the only way up).
Further, as you approach Lonavala, there's a big tunnel and a straight road after that, and a left where you'll find NH4 exit to Pune. You have to take this exit.. DONT proceed straight at this point.
Here, you'll be back on Nh4, .. and its Nh4 all the way to Pune from here.