Not really, the best way to come into San Diego is Hwy 8, however you will be driving through desert which can be hot, drive it at night is best. You will have to climb one mountain 6% grade, but it is fairly short, then it's about an hour or less to San Diego, depending where you're going exactly. I do not recommend taking Hwy 10 into Los Angeles to hwy 5 down to San Diego because of traffic and you will have to go over the famous Grapevine which is a big mountain! Hwy 15 is somewhat better but not much. I don't believe you can get to San Diego without driving over a mountain. I travel a lot and we usually take hwy 15/395 if we are going north or hwy 8 if we are going east. Hwy 8 is the shortest route for driving over a mountain, I think. Good luck! I lived in Tulsa for awhile and I always drove down through Texas to hwy 10 to Tucson AZ and hooked up with hwy 8 to visit my family in San Diego. It was the easiest drive for me. I now live in San Diego again, we are surrounded by mountains, your least or shortest time climbing over a mountain is entering from the east by way of hwy 8.