Hello. Recently I've been studying the Caro-Kann defense, and I've played it of course. But the real problem that I've faced when I play the Advance variation: the weak b5-e8 diagonal. So I suggest a new novelty, a move that already exists in the Najdorf Sicilian and caracterize it: a6 !!
[Variant "From Position"]
[FEN "rnbqkbnr/pp2pppp/2p5/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3"]
3... c5 4. c3 (4. dxc5 a6) 4... a6
lichess.org/analysis/rnbqkbnr/pp2pppp/2p5/3pP3/3P4/8/PPP2PPP/RNBQKBNR_b_KQkq_-_0_3#8
I think this a6 move is very strong when playing defenses that contains a c pawn move, because you've weakened that deadly diagonal. This line is also not that known because this loses some time for just one prophylactic move, but it's worth it because you don't want any dangerous thing to come to b5.
[Variant "From Position"]
[FEN "rnbqkbnr/pp2pppp/2p5/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3"]
3... c5 4. c3 (4. dxc5 a6) 4... a6
lichess.org/analysis/rnbqkbnr/pp2pppp/2p5/3pP3/3P4/8/PPP2PPP/RNBQKBNR_b_KQkq_-_0_3#8
I think this a6 move is very strong when playing defenses that contains a c pawn move, because you've weakened that deadly diagonal. This line is also not that known because this loses some time for just one prophylactic move, but it's worth it because you don't want any dangerous thing to come to b5.