Mild hybrids are slowly gaining ground in the automotive industry, and for good reason. A 48-volt system can improve efficiency through extended stop-start activation, brake regeneration and engine-off coasting, and it's less complex than a plug-in hybrid getup. Some systems, though, one-up the mild hybrid's efficiency push with an electric motor that can provide benefits beyond efficiency. 

The 2019 Mercedes-AMG E53's mild hybrid powertrain delivers both thrift and thrust in spades. Its subtle looks are perfect for people who might want some extra pep in their step without shouting it from the mountaintops, making it the muted option for those who might not want boisterous visuals present on AMG's most powerful offerings.

Looks might deceive

If you're going for an under-the-radar approach to performance, the E53 -- or any other large Merc destined for fancy men in expensive suits -- fits the bill. The looks are understated, with very few hard lines between the front and rear. It looks like a carbon copy of every other mainline Mercedes sedan, which it's supposed to. Even though the design language debuted back in the 2014 model year, it still looks great.

The only real allusions to performance on the E53 are the AMG grille up front, the four round tailpipes out back and, of course, the rear and side badges, which can be optionally deleted for some proper stealth. Trading the chrome bits for gloss-black trim is worth every penny of the $650 upcharge. Keener eyes will also note different wheels; my tester rocks a $750 optional set of 20-inch alloy wheels with black accents. But while the rollers look the business and fill the wells nicely, there are some trade-offs in ride quality. More on that shortly.

While I thought the sport-sport-sport motif in the similarly-sized AMG GT53's cabin was a little claustrophobic, I have no such qualms about the E53. That silly high-sided center console is gone, and with it the least ergonomic shifter I have ever experienced. Here, everything is nice and low, adding a bit more airiness to the interior. There's still ample storage space in the center console, and I think the column-mounted shifter is much better to use at all times. While the cupholders are easier to reach, the wireless phone charger is still hidden behind them, locking your phone away if you deign to bring drinks into the equation.

In traditional Mercedes sedan fashion, the E53 has more than enough visibility in all directions. It's both airy and comfortable, thanks in part to my tester's $1,320 massaging front seats, which are my favorite in the industry. The $2,990 Nappa leather upgrade makes everything feel really expensive, although spending $1,600 for a fancy headliner seems like a waste. Both rows are plenty cushy, with ample space for tall passengers in the back. Going even farther back, the trunk can accommodate groceries, golf bags, long-weekend suitcases, you name it. It may not have the ease of access that a hatchback offers, but it's still capacious as heck.

Mean green machine

Every 53-badged AMG carries the same potent powertrain. It starts with a 3.0-liter turbocharged inline-six, which puts out 429 horsepower and 384 pound-feet of torque. That's supplemented with a 48-volt mild-hybrid system that packs both an integrated starter/generator and an electric compressor, the latter of which can provide an extra 22 horsepower and 184 pound-feet of torque.

The result is phenomenal. There's a small gauge at the bottom of the digital cluster that tracks whether the EQ Boost system is charging or sending power to the wheels. It doesn't even take a full stomp to see the gauge's needle swing toward power, and when that happens, the E53 just pushes itself forward, but it's so well integrated with the gas engine that it feels like a singular entity shoving the car along. It's a solid 90% of the AMG 63 experience, at less than 90% of the price.

My tester sports the $1,250 exhaust upgrade, which is a two-mode system that makes the car sound surprisingly beefy. There's just a hint of straight-six rasp in there, but by and large, I appreciate the resulting noise, even if I think it's trying more than a little to sound like a V8.

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Whereas the GT53 I drove relied on adaptive dampers, the E53 comes standard with a sport-oriented air suspension. I'm a huge fan of Mercedes-Benz's air suspensions, and the story stays the same here. In its most comfortable setting, it does a commendable job handling bad roads, although I wish it could be a bit smoother; some of that is due to the car's sportier setup, and the rest likely comes from the upsize 20-inch wheels wrapped in thin Pirelli P-Zero summer tires (245/35 front, 275/30 rear). Sticking with the stock rollers should provide more plushness.

The remainder of the E53 driving experience is aces. The steering doesn't provide a whole ton of feedback, but it's quick to respond and the steering wheel feels nice to grip. Save for a bit of summer-tire noise, the cabin is mighty quiet, thanks in part to my tester's $1,100 Acoustic Comfort package, which adds cabin insulation and a sound-absorbing membrane in both the windshield and side windows.

If you're concerned about how much gas AMG's V8s suck down, and it's a lot, you'll be pleasantly surprised with the E53. The EPA rates this sport sedan at 21 miles per gallon city and 28 mpg highway, which trounces both the BMW M550i xDrive (18 city, 25 highway) and the outgoing Audi S6 (16 city, 24 highway) -- the feds have yet to publish test results for the rejiggered 2020 model. Best of all, these were numbers I have no trouble achieving on the regular, even with my foot occasionally attempting to friction-weld the gas pedal to the firewall.

Old tech doesn't mean bad tech

Even though the E-Class is just a couple of model years old, it snuck in ahead of Mercedes-Benz's MBUX infotainment system, the latest and greatest with doodaddery like a digital assistant that can understand natural-language requests and augmented-reality turn-by-turn directions. Despite being a new variant, this E53 still rocks the old COMAND system, but age is just a number. The system still feels plenty fresh, with graphics that aren't dated, decently short boot-up times and ample responsiveness.

Whereas the GT53 I drove used a new version of the system's touchpad, I actually prefer the E53's older setup, which retains a rotary dial for easier access to the dense forest of menus and submenus that, while daunting at first, can be committed to memory relatively easily. The screen's 12.3-inch size makes multitasking simple, with a small navigation map hanging alongside the radio or whatever else I have open.

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The 12.3-inch screen to the right is paired with another 12.3-incher that stands in for a traditional gauge cluster. It's quite powerful in its own right, offering three different design layouts and a wide variety of what can actually be displayed. It's a little tougher to figure out than, say, Audi's Virtual Cockpit, but it's all done using the slick little touchpad on the left of the steering wheel (the one on the right side works the infotainment). All this stuff is standard on the E53, too.

In terms of the usual safety systems, the E53 packs standard forward collision warning, automatic emergency braking and blind-spot monitoring. A surround-view camera and park assist are a $1,290 add-on. All the good stuff is tucked away in the $2,250 Driver Assistance Package, which adds full-speed adaptive cruise control, active lane-keep assist, active lane-change assist, route-based speed adaptation and evasive steering assist. It's a hands-on system, and it's one of the better ones, with smooth movement on both axes, and it's not so heavy-handed that it lulls me into a sense of false security.

How I'd spec it

My tester's base price of $72,500 has ballooned to $98,310 after Mercedes-Benz's options frenzy, but as always, I can do better. I'll start with the $720 Lunar Blue metallic paint, but I'll skip the larger wheels in exchange for more ride comfort. The $650 Night Package and $1,000 panoramic roof are must-haves in my book, and I'll spring for the $800 lighting package that adds adaptivity to the LED headlights.

Inside, I'll drop $2,990 for Nappa leather because I don't like the stock vinyl, and dark-brown wood veneer trim is a $0 upgrade, so why not. Winters get cold, so I'll spend $1,050 on a package that includes heated armrests and a heated steering wheel. It's free to add Nappa leather to the steering wheel, and who am I to look a gift horse in the mouth?

I'll cap it off with $1,320 for massaging seats, $450 for front seat ventilation, $1,100 foor the sound-deadening package and $1,250 for the active exhaust. That leaves me with a much more palatable $83,880 window sticker, less destination. I still can't afford it, but now I can't afford it slightly less.

Down to brass tacks

The E53's primary competitors are the Audi S6 and the BMW M550i xDrive. The Audi S6 has a new version coming for 2020, with its own mild-hybrid setup, but nobody's driven it yet so I can't speak to it, and I'd pick the Merc over the outgoing S6 all day. The BMW M550i xDrive doesn't have a hybrid system, but it's quicker than the last-generation M5, although I'm not in love with BMW's current interiors. The E63 is always available, too, but that $30,000 window-sticker premium is mighty dear. There are some fringe competitors, like the Lexus GS F, but that car offers sub-E53 performance at a starting price some $10,000 higher. Yikes. 

Mercedes-Benz has a real gem on its hands with the E53. This new EQ Boost system not only is the future, it proves that the future doesn't suck.