The Auto Expo 2016 saw participation from nearly all car-makers and it was a success with many new cars/bikes revealed/launched but the 2018 one it seems has got off to a rocky start with major car-makers like the VW Group (VW, Skoda, Audi, Porsche etc) pulling out over ROI concerns (return on investment) and effectiveness of participation.
Not just Volkswagen, Nissan and Ford are also likely to skip the event due to lack of new products to showcase. Participation at the Expo is expensive and without any new products coming or even with any plans for new products, car-makers think it is better to have an event outside the Expo for much cheaper and greater effectiveness as various launches get lost in the Expo Hype. On the other hand expect Kia, SAIC etc to mark their presence at the Expo making up for the absence of these car-makers.
Source- ET Auto