Eco-driving is a way to improve performance — mainly energy consumption — of road vehicles by computing an optimal speed and gear shifting profile based on vehicle data and road profile, e.g. slopes or speed limits. It mainly focuses on long haul scenarios such as highways, considering longitudinal movement only. Lateral acceleration of a vehicle is a critical quantity both in terms of comfort and safety, but its impact on fuel consumption or emissions is rarely considered or believed to be limited , as it does not affect directly the operating point of the engine. However, on country roads which usually present much stronger curvatures, lateral acceleration may be a critical constraint. In this paper, the impact of lateral acceleration limits on optimal solutions to multi-objective eco-driving is investigated. It is found that it may play an even more critical role than longitudinal acceleration with respect to fuel consumption and NOx emission. As a consequence, the choice of limits to lateral acceleration on curvy roads should be set very carefully in order to achieve a balance between energy saving, drivers comfort and travel time. The results of this work are validated on a high-feasibility Hardware-in-the-loop (HIL) system calibrated with data from Real Driving Emissions tests.