NEW DELHI, March 19 -- Maruti Suzuki India Ltd, the nation's top carmaker, has boosted dealer margins for three of its highest-selling models, underscoring a weak domestic car market and increase in operational expenses at its dealerships saddled with rising inventory.

Margins have been increased by Rs3,000 per vehicle on Maruti's Dzire (a compact sedan), Swift (a hatchback) and Vitara Brezza (a compact sport utility vehicle), said three people with direct knowledge of the development.

The step by Suzuki Motor Corp. unit took effect in January and is expected to offer additional liquidity to dealerships at a time when demand has dropped.

The dealers are also facing a credit squeeze after the crisis at Infrastructure Leasing and Financial...