"My car is not as new as my friend's."
Translation:Mi coche no es tan nuevo como el de mi amigo.
...As (adjective) as...
...Tan (adjective) como...
There's several other translations of as, depending on context. It could always be translated as "...so (adjective) like..." ---My car is not so new like my friend's. --- More awkward in English, but may be less confusing than the repeating as.
I got this wrong. just for grins, I let google translate look at my answer and duo's. "Mi coche no es tan nuevo tan mi amigos." was translated perfectly. I guess google translate is a dumb as I am when it comes to espanol translations. I do understand what I did wrong now, so I don't need any coaching. Just thought it was interesting. The intricate nuances of the language are too complex for google.