The Gist
Three dark, full-bodied South American reds look basically alike — the difference is the green note. Malbec has none; Carménère has a pungent jalapeño character; Chilean Cabernet sits in between with a restrained cedar/green-pepper hint. That single axis (how green the wine is) sorts them.
Mechanism
Three testable South American reds share dark color, high alcohol, full body, and new oak influence — yet each has a distinct chemical identity. Malbec: violet and blue-fruit character, velvety tannin, zero pyrazine. Carménère: high residual IBMP (jalapeño pyrazine), dark cherry, chocolate-oak, medium-soft tannin. Chilean Cab Sauv: lower IBMP than Carménère, cassis-dominant, graphite/pencil structure, firm tannin.
The green-note intensity is the primary axis: absent = Malbec. Jalapeño-pungent = Carménère. Restrained/cedar = Chilean Cab S. Carménère is the most frequently misidentified grape on the entire Pour Advice list. If you see a dark, full-bodied Chilean red — interrogate the pyrazine character before the fruit profile.
Deeper mechanism
Carménère's IBMP-degrading enzyme has lower activity than Cab Sauv's. The jalapeño note in Carménère is more aggressive and persistent because it is genuinely harder to degrade out of the grape. The dark chocolate from oak in Carménère is also more prominent because Chilean producers typically use heavier oak to balance the grape's natural weight.
Confusion analysis
Carménère vs. Cab Sauvignon (Chile)
Carménère: jalapeño more pungent, chocolate more prominent, tannin softer. Cab S: green note more restrained/cedar, graphite/pencil more dominant, tannin firmer.
Malbec vs. Carménère
Malbec: zero green note, violet/plum/blueberry, velvety tannin, no jalapeño ever. Carménère: jalapeño present, darker cherry, chocolate oak. The presence or absence of any green note separates them immediately.
Related varietals
This concept comes up when tasting: Cabernet Sauvignon, Carménère, Malbec