This paper proposes an energy-saving adaptive cruise control (ACC) which exploits the future trajectory of the preceding vehicle to minimize unnecessary braking. By suitable design of the model predictive control terminal set, the proposed eco-ACC avoids unnecessary braking and improves fuel economy, while guaranteeing safety and limited online computational burden. Simulations and experiments show the efficacy of the approach and confirm fuel saving, when the eco-ACC is compared to baseline ACC formulations.