You'll be fine... I took almost that exact same route in my Jetta... 105HP and ~3000 pounds unloaded. I was fully loaded +2 passengers and had the HPV on my roof (think parachute from a huge frontal area ).
So going uphill kinda sucked from my aero drag (I really couldn't handle more than 60mph) - but with a semi far in front, no problem I was more worried about cross winds from the thing on my roof
Time is the best teacher. Unfortunately it kills all its students.
I've taken my VX through the santa cruz mountains with no problems. In fact, I actually commuted with the VX (96HP?) daily through the santa cruz mountains.
I had an 82 Celica rated at either 92 or 96hp. The car had worn rings and was probably putting out 60hp (0-60 took over 30 secs). I also took that car over the santa cruz mountains, the grape vines from SF to LA and I took that road often since I went to college in San Diego.
Had absolutely no issues. The cars just arent' fast going through the mountains, but so what... I drive slow on straight away trying to keep over 50mpg! Can't be any worst going through the mountains.
I have a 93 Swift SOHC 1.3 5spd. Same as a Metro but with the 4 cylinder engine rated 70 hp. I've taken it on many trips, over 13,000' in the Rockies, 10,000' in the Sierras, climbing out of Death Valley from sea level to 7,000', long road trips of over 3000 miles. Plenty of power to exceed the speed limit in all those conditions. Cruising at 80 on the highway at high altitudes in mountainous areas not a problem. Average gas mileage on the highway is nearly 50. I love the little car for trips. Don't know if the 3 cylinder version would be acceptable for the trips I do, but I haven't tried one.