Zero-emission vehicles are a central component of plans to eliminate greenhouse gas emissions from California’s transportation sector. Because these vehicles generally have higher purchase prices than conventional vehicles and represent a new technology that many households are hesitant to adopt, it is important to find ways to incentivize the adoption of these vehicles. A range of methods have been tested globally, including monetary incentives and stickers that allow these vehicles to access high-occupancy vehicle lanes. This report assesses the potential use of express lane discounts as a driver of ZEV adoption by testing the effectiveness of a range of discount scenarios. These scenarios are built upon a baseline scenario that incorporates adoption drivers from existing policies and market growth trajectories. This analysis treats the express lane discount as a monetary incentive. The researchers find that providing even very large discounts for express lane usage to zero-emission vehicles would only slightly increase vehicle sales but would make these lanes much less capable of serving their other purposes. As part of this project, an Excel tool was developed that allows users to test their own scenarios. As an alternative to providing toll discounts to owners of new zero-emission vehicles, the authors recommend developing targeted incentives that focus on low-income and disadvantaged communities and are available to households that purchased pre-owned vehicles.