Hyundai Sonata Eco Delivers 32.5 MPG

Hyundai Sonata Eco Delivers 32.5 MPG

In this Under the Hood installment, we look at Hyundai’s updated 1.6L “Gamma” turbo-4 in the Sonata Eco. It may be balky off the line, but editors call it quiet, smooth and plenty powerful, even in Eco mode. Sport mode is more fun.

Hyundai’s improved 1.6L turbocharged “Gamma” 4-cyl., one of 38 nominees under consideration in the 2015 Ward's 10 Best Engines competition, makes a compelling argument as a hybrid alternative, with a base sticker price of $23,275.

The Gamma turbo, driving the midsize Sonata Eco sedan, came to our Michigan office in October for review. Hyundai offered up this engine for evaluation two years ago in the Veloster Turbo, and it didn’t make the cut, partly because the competition was fierce among 4-cyl. turbos.

That was the year we picked 2.0L turbos from GM, BMW and Ford. Hyundai engineers took this engine back to the woodshed to make some adjustments, and it returns with less horsepower in a bigger vehicle that is about 400 lbs. (181 kg) heavier, the new Sonata Eco, which is tuned for fuel efficiency.

On paper, given these factors, this engine should feel underpowered and sluggish. Hyundai turbocharged direct-injection engines have disappointed us for being raucous without feeling all that powerful.

But a number of editors have driven the Sonata Eco, and their comments are favorable. To date, the car has delivered 31.2 mpg (7.5 L/100 km).

It’s balky off the line due to turbo lag/accelerator calibration, but editors say the engine is quiet, smooth and plenty powerful, even in Eco mode. Sport mode is more fun, with transmission shift points coming at higher RPM, but fuel economy is bound to suffer.

So then the question is, does this version feature enough new technology to merit a close second look compared with the Veloster Turbo reviewed two years ago?

Improved Airflow, Higher Compression Ratio

Hyundai folks briefed us on this engine and said they redesigned the intake runners to reduce weight and improve airflow into the turbocharger. They also switched to an electric wastegate for more accurate boost control and to step up mid/high-load fuel efficiency.

The improved engine also has a higher compression ratio and a low-friction roller chain, both of which help boost fuel efficiency.

The Veloster Turbo used a 6-speed dry DCT while the new Sonata gets a 7-speed DCT with a higher torque capacity (246 lb.-ft. [334 Nm]). Hyundai says the new Sonata is the first midsize sedan using a 7-speed DCT.

Note also the horsepower peak still doesn’t arrive until 5,500 rpm after a fair amount of caning. Meanwhile, the Volkswagen 1.8L turbo-4 that won last year reaches peak hp by 4,800 rpm.

The 1.6L’s competition this year, besides VW’s excellent 1.8L turbo, will be Mini’s 1.5L 3-cyl. turbo, Alfa Romeo 4c’s 1.7L 4-cyl. turbo, Ford Fusion’s 1.6L turbo I-4 and 2.0L turbo-4s from Volvo, VW, Audi, Toyota, Subaru and Mini.

Oh, and Hyundai will have a 2.0L turbo in the mix, too.

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'15 HYUNDAI SONATA ECO 1.6L TURBO Specifications

Engine 1.6L DOHC 16-valve GDI all-aluminum 4-cyl.
Power (SAE net) 177 hp @ 5500 rpm
Torque 195 lb.-ft. (264 Nm) @ 1500-4500 rpm
Specific Output 111 hp/L
Valvetrain Dual Continuously Variable Valve Timing
Bore x stroke (mm) 77.0 x 85.0
Compression ratio 10.0:1
Transmission 7-speed dual clutch
Curb weight 3250 lbs. (1,474 kg)
Sticker price $28,560
Recommended fuel Regular unleaded
Fuel economy 28/38 mpg (8.4-6.2 L/100 km)


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