When the solar wind interacts with a small obstacle like Mars, protons and alpha particles behave quite differently at scales of the order of the size of the obstacle. Although alpha particles can contribute up to about 20% to the solar wind momentum and energy flux their contribution to the interaction has not yet been investigated. Meanwhile recent observations by Mars Express indicate that penetration boundaries could be different for alphas and protons. We use both test particle simulations and global hybrid simulations including self-consistently solar wind alpha particles to investigate their behaviour at the bow shock and evaluate their contribution to the transfer of momentum and energy to the Martian induced magnetosphere.