Mercedes-Benz is adding to its line with three new models, and at the same time giving them the designation of the 53-series. We had our first chance in October in the E-Class Coupe (designated the E-53), and took it on a trip to Southern California.

These new additions to the Mercedes wheelhouse are actually mild hybrid vehicles to some extent, as the engineers have added what is called an EQ Boost starter-alternator that is fitted between the engine and the transmission. What this does is build up a high charge of pressure through the electric auxiliary compressor without any delay that provides a faster increase in torque for acceleration.

It also ads an additional 21 horsepower to the package and 184 lb.-ft. of instant torque. This allows the coupe to get going very quickly, negating any turbo lag that inherently comes with a standard engine setup. While this electric boost is doing its thing, the turbocharger is building up pressure and kicks in giving the inline V-6 plenty of off-the-line power.

The AMG version comes in at 429 total horsepower and 384 lb.-ft. of torque. This combination continued to give us pleasure each and every day during out test drive. This new starter-alternator also drives a new 48-volt electric system in the car that powers things like the water pump, oil pump and anything else that was previously done with a belt drive on the front of the engine.

It also powers the regular 12-volt items like the infotainment system, dashboard and lighting features. Cool thing here is that with the higher voltage at work, the wires going to the different places can be smaller with less weight, meaning better mileage.

Since the belt has been eliminated from the front of the engine, there is now more space. The engineers, of course, have used it up by adding an exhaust gas turbocharger to the space that is much more efficient being closer to the motor.

This whole system adds up to all kinds of electric and mechanical technology that 10 years ago would not even have been in the running. Our biggest question was would it all come into harmony and produce a better outcome?

After our second week with the system, this one giving us much more city street time, we were very impressed both with the responsiveness and gas mileage of the 53 series. We ended the week at a better-than-EPA estimate of 25.3 mpg, not bad for a true four-door vehicle, or as Mercedes puts it a four-door coupe!

Oh and lest we forget, this new mix of electric and gas-driven engine will propel the coupe to 60 in a mere 4.4 seconds. Oh yeah, that is a rush in anyone’s book.

The CLS53 comes with different driving modes included: eco, comfort, sport and sport plus, the later introducing some really great stiffness and acceleration into the mix along with and exhaust note at each shift point that kept us wanting for more of that sweet sound.

All of this added up the to a sedan that really took us by surprise out of the Mercedes wheelhouse. This is a vehicle that we, as empty nesters, could become very at home with.

Not only is CLS53 a gorgeous offering in the world of cars, it also handles like a dream, just sailing down the road. If fact, it practically drives itself — it is so loaded with safety technology. We have driven a number of different vehicles that, when the adaptive cruise control is set, they will center themselves in the lane and stay there with ease.

Mercedes has put some serious engineering into their version of this technology, and we loved the way it performed. After making sure all the right boxes were checked in the setup menu of the CLS53, we set the cruise after hitting Interstate 15 and headed north.

Not only did it center the CLS53 in the lane and maintain a set distance from any vehicle it came upon, it would even slow down to take tighter curves on our route, and would speed up and slow down according to speed limit signs it saw along the way.

This turning technology worked flawlessly as we headed up Provo Canyon, allowing us to test it on the curvy roads to Heber. It would even slow to as low as 25 mph to make the sharpest turns along the way. It was the best version of this technology that we have seen to date, and really made the drive so much easier.

Inside, the seats are so comfortable to sit in they gave our backs a rest every time we drove it. The inside of the Mercedes is loaded with luxury, including leather seats that are standard and included a beautiful stitching that continued on the dashboard and door panels, along with soft touch points everywhere in the interior.

The LED accent lights inside the Mercedes could be changed to any color imaginable, and really should have been called mood lights because they set the mood for the drive, making driving the CLS53 at night our favorite thing to do. Having a color mixing pallet with endless choices was just too much fun to play with, kind of like having a new grown up toy at our beck and call.

The twin 12.3-inch high-resolution displays that make up the cockpit give the Mercedes a very futuristic design and feel. The engineers have even put small touchpads on the steering wheel that can control both displays so we never had to take our hands off the wheel to make adjustments. These can also be controlled by voice.

The new CLS53 four-door coupe proved to be enticing, exciting and engaging every time we had the chance to go out for a drive. It is refined enough for folks like us and advanced enough for even a younger generation, add all the sporty add-ons and the arithmetic made perfect sense to us.

Base Price: $79,900

Price as Driven: $87,205