– Carmel Valley, California

The roads between the Mercedes-Benz research center in Sunnyvale, California, and our hotel in Carmel Valley are choked with traffic and we’re crawling along. Fortunately, I’m doing very little behind the wheel. Distronic Plus adaptive cruise control and Steering Pilot engaged, the 2017 Mercedes-Benz E300 brakes when traffic slows, accelerates when it clears, and even steers to keep me in my lane. The tech lets me keep my hands off the wheel for up to 60 seconds in high-speed freeway driving; below 20 miles per hour, I never need to steer at all. Suddenly traffic jams don’t seem so tiring.

“What we’ve found is that a stress-free driver is actually a better driver,” agrees Bart Herring, Mercedes-Benz USA’s general manager for product development. At the helm of an E-Class, he boldly promises, “you should arrive feeling better than when you left.”

While it’s great to cede some driving control to the car – Mercedes notes its features are assists, not a replacement for human drivers – the 2017 E300 is also supremely satisfying to drive manually. It’s luxurious when you want to treat yourself, sporty when you want to hustle, and pretty from every angle.

It’s luxurious when you want to treat yourself, sporty when you want to hustle, and pretty from every angle.

The W213-generation E-Class manages that great trick we all wish we could achieve: It grows while still losing weight. Total length increases 1.7 inches and the wheelbase gains 2.5 inches....