I know someone who raised his detached garage top fit a vehicle. He prefabbed some wall 'extensions' and placed them next to the garage. He then had a crane come and lift the roof and he threw the extensions in and secured them. The roof was placed back down, and re-secured. Afterwards, he just finished the exterior of the extensions and viola - taller roof. Then there was the matter of installing a new door.
He had a friend who owned a crane though, so that was his cheapest option.