Inside Seven - Caltrans, District 7 - Monthly Newsletter "Most travelers think the portion of I-5 called the Grapevine begins at the north end of Castaic in the Santa Clarita Valley where the freeway begins a northerly climb at Parker Road -- and where the California Highway Patrol closes the freeway when snow or icy conditions northward prohibit safe travel. But this is not where the actual Grapevine is located. What they would be traveling on, instead, is what is most commonly known as the beginning of the five-mile grade where I-5 sharply rises to the north at a grade of 5% -- and the beginning of a 40 mile journey over the Tehachapi Mountains from northern Los Angeles County to the San Joaquin Valley in Kern County. After the five mile grade, comes Templin Highway at about the 3,000-feet level. Proceeding north one encounters 22.5 more miles north on a rolling, meandering drive by Frazier Mountain through the Gorman area and the highest point of the drive at an altitude of 4,183 feet, and the summit of this famous drive. Continuing northerly from the summit is a slight drop in altitude and in six more miles one reaches Fort Tejon, a state historic monument. Fort Tejon was established in 1854 to suppress stock rustling, which was rampant at that time, and to protect the Native Americans in the San Joaquin Valley. It is here where the actual portion of freeway known as the Grapevine actually begins." In essence, you start off at around sea level or so in LA and drive for the next 60miles and reach the peak at 4,183ft.. About 5-8miles of it gains altitude at about 5% grade but by then your hybrid battery is running low. I had no issues and even going over the pass I could still manage 50mpg from Sacramento to Glendale and 47mpg back. In reality I do not see the grapevine as any worse than driving from Sacramento (approx. 20ft. ASL) to Donner Summit (7,300ft. ASL at peak) on I-80. Approx. 88miles and high speeds.
grapevine isnt that big a deal really. and going north over it is indeed worse as when you drive south the uphill is much steeper but shorter and then you have a long brake burner of a drive till you hit the bottom. either way nothing to worry about in a prius vs any other car.