The Grapevine is a mountainous area between Los Angeles and the central valley. Would imagine the elevation and turns could seriously affect battery life but not sure how much.

Makes me wonder if a solar panel hood/roof would help any.

I own a Model 3 long range, and have put about 2500 miles on it so far. I've always gotten pretty close to the estimated range. Even on extreme hills like Shoreline Highway heading to Agate state park beach, I didn't notice anything excessive.

Remember, hills require more energy to climb, but you regain the energy on descent which is captured by regenerative braking. It's not 100%, but it's efficient enough that it doesn't make a significant difference. And, again, driving 20 mph through some switchback curves is a hell of a lot less wind resistance than driving 75mph on the freeway.

I still say you need some evidence to back up the claim that you got less than half the rated range on a Tesla. You better believe the media would be all over it if that were true.

The Grapevine is a mountain pass from the Central Valley to LA County, approximately 20 miles long, with rolling hills, that goes up to 4100 feet of elevation gain. (But note that common usage is to refer specifically to a 5 1/2 mile stretch that is the steepest.)

You're absolutely going to not get the rated battery life there.

Meh. Even in my turbocharged car, I get virtually the same mileage in the mountains going from sea level to over 8000 feet and back down vs what I get on a wide open freeway, and that's WITHOUT regen.

Obviously if you only go up but not down that's a different story, but mountainous driving is not nearly so hard on range if it's a net of 0.

Perhaps you could also explain what the "Grapevine" is?