In this cnet report from SEMA cnet salivates over the the EcoRoutes ESP module for Nuvi navigation devices. The module is a small hideaway box that communicates with Nuvi units via Bluetooth and connects to (and is powered by) your vehicle's OBD-II diagnostics port. The device gathers information about your vehicle's performance and relays that info via a Bluetooth data connection to your Garmin Nuvi GPS device atop your dashboard. Using the Nuvi's touch screen there is a set of customizable gauges, the ability to view and clear fault codes when the Check Engine light comes on, and the ability to monitor real-time fuel economy and emissions data. It also data logs to track performance and interfaces with the EcoRoutes software that's already present on current Garmin devices.
