MANILA, Philippines - In the Makati financial district, that tantalizing smell in the air just might be a police car. The police force here is the latest to try out the idea of running a cruiser partly on used cooking oil from McDonald's restaurants. If it works well, the 60 percent diesel/40 percent French-fry-oil blend could become a standard fuel for the police fleet.

The Manila Times reported on Tuesday that the Makati Police Department's PNP-Bio Diesel Program will save the force about $22 per fill-up at current fuel prices, or the equivalent of more than $11,000 a year when spread among 10 patrol cars.

The police chief, Gilbert Cruz, and Professor Roel Judilla of the Mapua Institute of Technology co-developed the project, which filters the cooking oil and cools it before blending it with diesel. It's not just French-fry oil; it will come from a range of fast-food restaurants around the city, although McDonald's was the first donor and sent a representative to the press conference that kicked off the project.

Six months of testing are planned, said Judilla.