Hello all. I have just done a trip to Delhi (from Mumbai), Aug 2017, in my CNG vehicle. CNG is not a problem throughout, barring the distance between Udaipur & Jaipur (Kukas).
Route with CNG:
Mumbai (Kashimira CNG) - Vapi (Adani CNG) - Baroda (lots of CNG on highway) - Halol (2 CNG pumps) - Godhra (1 online pump, in the city) - Modasa (1 offline CNG pump) - Shaamlaji (1 CNG pump) - Udaipur (no CNG, but topping up at Shamlaji should reach you Udaipur) - Ajmer (No CNG) - Chittorgarh (No CNG) - Jaipur (CNG is in Kukas, dont take the Jaipur bypass) - Neemrana (CNG @ Rs 55 apx!) - Delhi (loads of CNG).
Great roads, super tarmac & amazing journey. You can check our experience at our webisode series :