SINGAPORE — Lamborghinis, Porsches and Bentleys fill the driveways of multimillion-dollar villas in Sentosa Cove. Yachts line the 400-berth marina nearby. A number of homes have guardhouses for security.

But signs of a slowdown are just beneath the shiny surface. The grass on front lawns has turned brown from neglect. Two condominiums last summer went for less than half their original price, while others sit empty.

At the W Residences, one of the newest condominiums, fewer than half of the units have been sold. Walking around a lavish showroom apartment with infinity pool, Sheena Teng, a sale consultant for City Developments Limited, the developer of the W Residences, says that prospective buyers in Sentosa once were rich Asians looking for vacation homes. She said most of the current occupants at the W Residences were expatriate professionals in Singapore — and they are renting.

As Singapore pitched itself as a place for Asia’s rich, Sentosa Cove attracted many wealthy Chinese, Malaysians and Indonesians. But the momentum behind that boom is slowing, putting the gated community at the center of the weakness.