This paper describes a new method to synthesize driving cycles, where not only the velocity is considered, yet also the road slope information of the real-world measured driving cycle. Driven by strict emission regulations and tight fuel targets, hybrid or electric vehicle manufacturers aim to develop new, more energy and cost efficient, powertrains. To enable and facilitate this development, short, yet realistic, driving cycles need to be synthesized. The developed driving cycle should give a good representation of measured driving cycles in terms of velocity, slope, acceleration and so on. Current methods use only velocity and acceleration, and assume a zero road slope. The heavier the vehicle is, the more important the road slope becomes in powertrain prototyping (as with component sizing or control design), hence neglecting it leads to unrealistic or limited designs. To include the slope, we extend existing methods and propose an approach based on multi-dimensional Markov chains. The validation of the synthesized driving cycle, is based on a statistical analysis (as the average acceleration or maximum velocity) and a frequency analysis. This new method demonstrates the ability of capturing the measured road slope information in the syntesized driving cycle. Furthermore, results show that the proposed method outperforms current methods in terms of accuracy and speed.