I believe it can be done by modifying the query somewhat like this (newlines added for readability); although I'm not sure about the boost syntax:
(car AND (color:blue^0.9 OR color:[* TO *]^0.1)
AND (price:[* TO 10000]^0.9 OR price:[* TO *]^0.1)
AND (model:Toyota^0.9 OR model:[* TO *]^0.1))
Edit:
This solution seems to work quite as I intended in my implementation. Although I added to the weights for the preferred properties. ^1000 seemed to give them enough weight to win over the non preferred.