Local incentives may also be available; for example, the clean vehicle rebate in California is an additional $1,500 and Sonata Plug-in Hybrid is eligible for California’s Green Clean Air Vehicle Decals that allow access to the HOV lanes. Pricing will be announced before the Sonata Plug-in Hybrid goes on sale this Fall. Although theoretically a non-ZEV state buyer could special order the PHEV, said Brandon Ramirez, Senior Group Manager, Product Planning, Hyundai won’t encourage it—partly due to dealer training, support and infrastructure issues that also require their own roll-out.

Sonata models
	Sonata HEV	Sonata PHEV	Sonata ECO	Sonata	Sonata 2.0T
Engine	Nu 2.0L GDI		Gamma 1.6L Turbo GDI	Theta 2.4L GDI	Theta 2.4L Turbo GDI
Engine power (kW)	115		132	138	183
Engine torque (N·m)	190		264	241	353
Compression ratio	13.5:1		NA	11.3:1	10.0:1
Total system power (kW)	144	151	132	138	183
Combined fuel economy (mpg)	41-42	40 93 MPGe	32	28-29	26

Powertrains. Both parallel hybrid powertrains—PHEV and HEV—use Hyundai’s Transmission-Mounted Electrical Device (TMED) coupled with a six-speed automatic transmission and the Nu 2.0L (1999 cm³) GDI 4-cylinder DOHC 16-valve engine with DCVVT (Dual Continuously Variable Valve Timing).

The second-generation hybrid system has been thoroughly enhanced from its predecessor:

• The downsized GDI engine features an aluminum block and head, a compression ratio of 13.5:1, and delivers 154 hp (115 kW) @ 6,000 rpm and 140 lb-ft (190 N·m) @ 5,000 rpm. Unlike the Theta II multi-port fuel injection (MPI) engine in the first generation Sonata hybrid (earlier post), Hyundai has not at this point implemented an Atkinson or Miller cycle in the Nu engine on these next-generation hybrids, Ramirez said.

• The electric drive motor is smaller (-0.4L), lighter (-3.7 lbs / -1.7 kg) and more powerful (+3 kW). The TMED electric motor (a Hyundai motor) for the PHEV and HEV versions is the same; however, due to its operation with higher voltage (360V in the PHEV vs. 270V in the HEV, the motor in the PHEV outputs 50 kW (67 hp) @ 2,330-3,300 rpm, vs. 38 kW (51 hp) @ 1,770-2,000 rpm in the HEV. Torque output is the same for PHEV and HEV: 205 N·m (151 lb-ft) @ 0-1,1770 rpm.

• The 6-speed AT features a high-voltage electric oil pump for improved efficiency.

• The hybrid control unit is lighter weight (-21%) and offers a higher power density (+24%).

• The new system features increased regenerative energy capture (+11.3%). Regen in both the hybrid and PHEV is not user adjustable—i.e., a driver can not select a more or less aggressive regen. As implemented, the regen function in the Sonata feels very mild—either a feature or a flaw, depending upon driver predilection.

• The on-board charger for the plug-in offers maximum efficiency of 91.7%.

The 2016 Sonata PHEV features a 9.8 kWh Li-ion polymer pack, the HEV a 1.62 kWh Li poly pack. LG Chem is the supplier of cells for both. The PHEV pack has a maximum power output of 68 kW, the hybrid pack, 56 kW. Click to enlarge.

Sonata PHEV is expected to deliver 93 MPGe combined in EV mode based on internal estimates. In charge sustaining mode, the Sonata PHEV is expected to return 40 mpg (5.88 l/100 km) combined based on internal testing. Recharge time ranges from less than three hours at a 240V Level-Two charging station to less than nine hours using a standard 120V outlet.

2016 Sonata Hybrid is composed of more than 50% advanced high-strength steel which improves torsional rigidity by 41%. Click to enlarge.

Drive modes. The 2016 Sonata PHEV has three operating modes:

• EV mode. EV mode, or all-electric battery charge depleting mode, can handle speeds up to approximately 75 mph (121 km/h). This is the default mode for the Sonata PHEV, and is recommended for city driving.

• Hybrid mode. In hybrid mode (charge sustaining mode), the Sonata PHEV operates much like its HEV sibling—one of the major exceptions being the lack of a Sport Mode, which is available on the Sonata Hybrid.

• Battery charge mode. A long press on the HEV toggle switch on the center console invokes battery charge mode, which uses engine power to run the traction motor as a generator to recharge the battery pack more rapidly.

In our relatively short test drive, we found this last feature to be very compelling and well implemented. A typical use case scenario would be starting out on a longer drive or commute in EV mode, and moving onto a high-speed highway some miles into the drive. The Sonata PHEV is perfectly capable of handling (legal) Interstate speeds on battery pack alone; however, such operation depletes the battery relatively quickly.

Assuming a city-type destination at the other end, or a low-emission zone, or something similar, the Sonata PHEV driver can toggle charge mode to replenish the battery pack on the highway. On our test drive, we had depleted the pack down to below 50%; toggling charge mode replenished the pack by more than 10 percentage points in less than 10 miles—enough for several more miles of all-electric range.

To implement the charge mode, Hyundai uses a 2-clutch system—one clutch between the engine and motor, one clutch within the transmission. Hyundai described such a 2-clutch approach to improving battery charging efficiency by using the electric traction motor for charging in 2013 at EVS 27 (Song et al.).

Charge by ISG. Song et al. Click to enlarge.		Charge by traction motor. Song et al. Click to enlarge.

… EV mode is limited until the battery SOC [state of charge] is recovered to the normal state. Moreover, if the battery SOC drops below the lower limit frequently, durability of the battery might be reduced. However, since the ISG uses a small motor with relatively low efficiency compared with driving motor, this charging process may decrease the total system efficiency. In this study, a battery charging control is proposed using a driving motor during vehicle stops to obtain the improved charging efficiency.

… To charge the battery using the driving motor, a 2-clutch system control was proposed which uses the engine clutch and the clutch inside the transmission. In this control, one friction element of AT should be disengaged to disconnect the motor from the driveshaft. The engine clutch is engaged and the engine operates the driving motor to charge the battery instead of ISG.

… Simulation results show that the battery charging using the driving motor has a higher efficiency and faster speed compared with the conventional battery charging system using the ISG.

—Song et al.

Top. The instrument cluster. The left gauge replaces the tachometer and indicates recharge (blue), eco-driving (green), and drive mode (EV/Eco in this case). The bottom of the gauge provides a graphical indication of battery state of charge. (A percentage SOC value is available on other user-selectable displays.) The center display, selectable from a button on the steering wheel, can display information such as remaining range; driving style (middle); or drive mode (bottom). Click to enlarge.

Exterior. Overall length and width of the 2016 Sonata PHEV/HEV has been increased by more than 1 inch compared to the 2015 Sonata HEV. Sonata Plug-in Hybrid uses the same functional design changes as the Sonata Hybrid to improve its drag coefficient to a class-leading 0.24 as well as provide visual cues to distinguish the hybrid models from other Sonatas. Changes include:

• Front active air flaps with automatic operation based on vehicle speed and engine temperature to reduce drag.

• A lower bumper air curtain uses accelerated air flow to form a curtain that reduces turbulent air drag.

• A center floor under cover allows for smooth air flow underneath the vehicle.

• A rear spoiler reduces drag effect for optimum aerodynamics.

• Eco-spoke alloy wheels with smaller openings reduce the drag generated by wheel spokes.

Visual changes to the Plug-in Hybrid’s exterior include a charging port on the driver front fender, unique grille, front and rear bumpers, front fenders, front and rear lights, chrome side sill moldings, Hybrid badging and an eco-spoke alloy wheel design. A charge indicator is located on top of the dashboard to make it easy to see the state of charge from outside the vehicle.

Passenger and cargo room. The Sonata PHEV and HEV offer best-in-class (mid-size hybrid sedan) front seat headroom and legroom, as well as passenger and cargo volume. Interior volume in the PHEV is slightly less than than of the HEV, due to some intrusion of the larger battery pack into the trunk space: 116 ft³ vs. 119.4 ft³. Passenger room is the same between the models: 106.1 ft³.

Blue Link app. Owners can manage and monitor the Sonata Plug-In Hybrid Electric Vehicle remotely via an exclusive Blue Link smartphone app. With the app, owners can access real-time data from their Sonata PHEV and perform specific commands such as starting the engine and locking doors. Plus, users can search for points of interest using Google with voice or text and have the directions when they start their Sonata Plug-in Hybrid.

The most useful feature of the app is managing the car’s charging schedule. The owners are given vehicle charging options that they can select while in the car, but users can also manage them remotely via smartphone. Immediate charge is the simplest option, as charging begins as soon as the Sonata Plug-in Hybrid is plugged in.

Individuals that have different electric rates at various times may want to schedule the charge. Users can do that with the new app based on time and date.

Safety. 2016 Sonata Plug-in Hybrid comes standard with seven airbags, including a new driver’s knee airbag. Electronic Stability Control, Vehicle Stability Management, Traction Control, ABS and a Tire Pressure Monitoring System with individual tire pressure display, and a rearview camera are also standard. Projector headlamps are standard while HID headlamps are available. Advanced safety technologies such as Forward Collision Warning and Lane Departure Warning are also available in this midsize sedan.

Sonata Plug-in Hybrid’s standard advanced Blind Spot Detection system is designed to alert drivers of an approaching vehicle in the next lane if the turn signal is activated. This Lane Change Assist technology is a segment-exclusive active safety feature. Drivers are first alerted of a vehicle in the blind spot by warning lights in the side mirrors.

When the turn signal is activated, the Lane Change Assist system determines the closing speed of any vehicle in the adjacent lane to determine if the lane change is safe. If the system determines the vehicle in the other lane is closing too quickly, it sounds an audible alarm to warn the driver that the lane change is unsafe. The Lane Departure Warning System uses a forward-facing camera to recognize lane markers. If the system detects the vehicle is headed outside the lane markers, a warning light on the dashboard illuminates and an audible sound alerts the driver.

Rear Cross-traffic Alert (RCTA) is another feature derived from the 2016 Sonata Plug-in Hybrid’s advanced Blind Spot Detection system. RCTA scans the areas to each side of the vehicle when drivers are backing out of parking spaces. If the system detects another vehicle is approaching from the side, the Sonata driver is given an audible alert. This system is another tool that helps Sonata drivers utilize the active safety technology.

Driving impressions. Overall, the Sonata PHEV is a pleasure to drive. The roomy cabin is comfortable, even in the back seat. The transitions from electric to hybrid mode are smooth, and noise is kept to a minimum. The HMI on the center console display is extremely usable, and provides good detail on energy flow and driving performance.

The driving route provided for the media event was essentially divided between stop-and-go driving down the Pacific Coast Highway through the small towns and cities dotted along it and higher speed (and relatively constant) driving on the 5. These are the conditions that show the Sonata PHEV at its best. However, there wasn’t much opportunity to get a sense of Sonata handling in higher-speed cornering, steep inclines, and winding roads.

On the route we drove, the Sonata PHEV (and HEV) handled and performed extremely well. As noted above, the Charge Battery function was a nice addition. Our sense, unconfirmed at this point, is that with the PHEV battery pack situated toward the rear of the car, the PHEV might have a tendency to wallow through a tight corner—as do most vehicles with a rear positioned battery pack.

Further, the acceleration off the line seemed just a tiny bit slow, although there is no hesitation.

All that said, however, Sonata is not targeting a high-performance buyer.

Although Hyundai has yet to announce pricing, the Hyundai team suggested the pricing would be compelling. If that is indeed the case, Hyundai may well advance the market for a mainstream, mid-size plug-in hybrid sedan beyond what its competition has yet been able to do.

Hyundai is also being aggressive with its warranties, including a lifetime warranty on the battery pack. Click to enlarge.

Competition. Hyundai is identifying Ford’s Fusion Energi and the Honda Accord plug-in hybrid as its PHEV competitors in the mid-size sedan segment. (For the Sonata HEV, the Camry Hybrid enters the competitive mix along with Fusion and Accord.)

Mid-size sedan PHEVs
	Sonata Plug-in Hybrid	Fusion Energi	Accord Plug-in Hybrid
Engine displacement	2.0L GDI	2.0L Atkinson	2.0L Atkinson
Engine power (kW)	115	105	105
Engine torque (N·m)	190	175	165
Electric motor power (kW)	50	88	124
Electric motor torque (N·m)	205	240	307
Battery pack capacity (kWh)	9.8	7.6	6.7
Transmission	6-speed AT	e-CVT	e-CVT
Total system power (kW)	151	145	146
Maximum EV speed (mph)	75	80	65
All-electric range (miles)	24	21	13
MPGe (charge depleting)	93	88	115
MPG (charge sustaining)	40	38	46

Resources

• Minseok Song, Seokhwan Choi, Gyeonghwi Min, Jonghyun Kim, Hyunsoo Kim (2013) “Improvement of Battery Charging Efficiency using 2-Clutch System for Parallel Hybrid Electric Vehicle” EVS27

• Insup Kim, Hyunsup Kim (2013) “Configuration Analysis of Plug-in Hybrid Systems using Global Optimization” EVS27