This is a bit of a long shot as I remember very little about this movie. I recall it being in the classic, glamorous Hollywood style of the late 1950s (possibly early 1960s), with the plot involving a mountain or hillside home where visiting cars would park on the edge of the hillside. The murder plot involved someone tampering I think with the gears of a car (or could have been the brakes) whereby someone (a female?) tried to drive off normally but only succeeded in driving off the edge of the hillside. Does anyone recognise this?

Angel Face (1952)
Starring Robert Mitchum, Jean Simmons
Wikipedia synopsis excerpt:
The following day, with Frank gone, Catherine prepares to drive herself to Santa Barbara. As she is about to leave, Charles asks for a lift, and, after Catherine puts the car in drive and steps on the gas, the vehicle screeches backward over the cliff. Catherine and Charles are killed in the crash. Following some investigation, both Frank and Diane are arrested for murder. Diane, who stands to inherit all of Catherine's wealth, has suffered a nervous breakdown and is incarcerated in a prison hospital.

http://en.wikipedia.org/wiki/Angel_Face_(1952_film)