Eco-driving is becoming more widespread as individual car-use behaviour is a cost-effective way of improving vehicle fuel economy and reducing CO 2 emissions. The literature shows a wide range of efficiencies as a result of eco-driving, depending on route selection, traffic characteristic, road slope, and the specific impact evaluation method. This paper follows this line of research and assesses the impact of an eco-driving training programme on fuel savings and reduction of CO 2 emissions in a well-designed field trial, focusing on the specific impacts according to road type. The methodology includes a comprehensive trial on different types of road sections under various traffic conditions; a processed dataset using R codes to integrate, clean, and process all the information collected; and a systematic method to evaluate the overall and specific impacts of eco-driving. The final results show a general fuel saving after eco-driving training of up to an average of 6.3% regardless of fuel and road type. Driving performance, as represented by selected parameters (average and maximum RPM, average and maximum speed, aggressive acceleration/deceleration), changed significantly after the training. The highest fuel savings are achieved on major arterial road sections with a certain number of roundabouts and pedestrian crossings. This work contributes to an understanding of the key factors for eco-driving efficiency according to road type under real traffic conditions. It offers greater insights for policymakers in road transport planning and for drivers when applying eco-driving techniques. of information and communication technologies (ICT) to improve transport efficiency [3]. However, the investments in these strategies are huge, and the implementations are usually complex and involve multiple stakeholders. Research has shown that the potential improvements in GHG reduction from advanced engine and vehicle technologies accounted for only 4-10% and 2-8%, respectively [4]. Meanwhile, eco-driving is becoming more widespread, as individual car-use behaviour is more cost-effective and could improve vehicle fuel economy and reduce CO 2 emissions by up to 45% [5].At the operational level, eco-driving is defined as a strategy which primarily seeks to change driving habits by following easily typified rules, i.e., using vehicle inertia, accelerating and braking smoothly, maintaining a steady speed, shifting gears at low RPM, anticipating traffic, etc. [6,7]. Eco-driving can not only improve fuel efficiency but also reduce road accidents and noise as a result of drivers' calmer driving patterns [8].The literature shows that the efficiency of eco-driving varies widely depending on the experimental design, the external circumstances, and the methods of impact evaluation [9]. The fuel savings before and after receiving eco-driving instruction in several field trials revealed that fuel reduction varies from 5% in the case of a single monitored vehicle [10] to 25% immediately after drivers were enrolled in a training course [9,11],...