New Delhi, June 18 -- Tata Motors' commercial vehicle business (TMCV) and Ashok Leyland shares have risen 12.4% and 15%, respectively, over the past four trading days, comfortably outperforming the Nifty Auto index's 3.6% gain.

What's driving the outperformance?

The biggest trigger is the recent plunge in crude oil prices. Brent crude has fallen 15% over the past five trading days to around $80 per barrel.

While lower crude prices benefit the broader automobile sector, the impact is particularly significant for commercial vehicles (CVs), where dependence on diesel remains high.

Alternative fuels remain far less prevalent in commercial vehicles than in passenger vehicles or two-wheelers.

Electric vehicle penetration in the CV segment ...