Really hope Tesla enables Apple Lossless.
For me, 256 kbps AAC is plenty good enough for in-car use. It's very difficult to distinguish from lossless even in quiet situations with good playback.
But the Tesla streaming and particularly "HD" digital radio has distortion characteristic of insufficient bit rate or mediocre codecs, scratchy harsh violin is the common symptom. The broadcasters also choose the bit rate and any other processing so it may be their fault.