McLaren's magical open-top 570S Spider simply redefines the term 'sportscar', blogs Road Test Editor Howard Walker We're cruising for caffeine. Carmel, south of San Fran, down Pacific Coast Highway to Big Sur. God's driving road. Thirty-odd miles of serpentine twists and turns. Frothy Pacific to the right, towering rock faces to the left. We'll be ready for that cappuccino on the deck at Nepenthe. This should be a tourist sightseeing meander. Speedo stuck at 30, ready to dive into every scen...