2018 Toyota Corolla iM vs. 2018 Chevrolet Sonic

Detailed Review, Specifications & Comparison

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The Corolla iM has standard Active Headrests, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the Active Headrests system moves the headrests forward to prevent neck and spine injuries. The Sonic doesn’t offer a whiplash protection system.

The Corolla iM has standard Pre-Collision System, which use forward mounted sensors to warn the driver of a possible collision ahead. If the driver doesn’t react and the system determines a collision is imminent, it automatically applies the brakes at full-force in order to reduce the force of the crash or avoid it altogether. The Sonic offers an available collision warning system without the automated brake feature that would prevent or reduce the collision if the driver fails to react.

The Corolla iM’s driver alert monitor detects an inattentive driver then sounds a warning and suggests a break. According to the NHTSA, drivers who fall asleep cause about 100,000 crashes and 1500 deaths a year. The Sonic doesn’t offer a driver alert monitor.

Both the Corolla iM and the Sonic have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, front seatbelt pretensioners, front wheel drive, height adjustable front shoulder belts, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights and rearview cameras.


The Corolla iM’s corrosion warranty is unlimited miles longer than the Sonic’s (unlimited vs. 100,000 miles).


The camshafts in the Corolla iM’s engine are driven by a hardened steel chain, with no maintenance needs. The Sonic 1.8 DOHC 4 cyl.’s camshafts are driven by a rubber belt that needs periodic replacement. If the Sonic’s cam drive belt breaks the engine could be severely damaged when the pistons hit the opened valves.

J.D. Power and Associates’ 2016 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Toyota vehicles are more reliable than Chevrolet vehicles. J.D. Power ranks Toyota fourth in reliability, above the industry average. With 12 more problems per 100 vehicles, Chevrolet is ranked 6th.

From surveys of all its subscribers, Consumer Reports’ April 2017 Auto Issue reports that Toyota vehicles are more reliable than Chevrolet vehicles. Consumer Reports ranks Toyota second in reliability. Chevrolet is ranked 15th.

Fuel Economy and Range

On the EPA test cycle the Corolla iM gets better fuel mileage than the Sonic:



Corolla iM




4 cyl./Manual

27 city/35 hwy

25 city/33 hwy



4 cyl./Auto

28 city/36 hwy

24 city/34 hwy


The Corolla iM has 1.8 gallons more fuel capacity than the Sonic (14 vs. 12.2 gallons), for longer range between fill-ups.


The Corolla iM offers an available continuously variable transmission (CVT). With no “steps” between gears, it can keep the engine at the most efficient speed for fuel economy, or keep it at its peak horsepower indefinitely for maximum acceleration. The Sonic doesn’t offer a CVT.

Brakes and Stopping

For better stopping power the Corolla iM’s brake rotors are larger than those on the Sonic:


Corolla iM


Front Rotors

11.7 inches

10.8 inches

Rear Rotors

11 inches

9” drums

The Toyota Corolla iM has standard four-wheel disc brakes for better stopping power and improved directional control in poor weather. Only rear drums come on the Sonic. Drums can heat up and make stops longer, especially with antilock brakes which work much harder than conventional brakes.

The Corolla iM stops shorter than the Sonic:


Corolla iM



70 to 0 MPH

175 feet

184 feet

Car and Driver

Tires and Wheels

For better traction, the Corolla iM has larger tires than the Sonic (225/45R17 vs. 195/65R15). The Corolla iM’s tires are larger than the largest tires available on the Sonic (225/45R17 vs. 205/55R16).

The Corolla iM’s tires provide better handling because they have a lower 45 series profile (height to width ratio) that provides a stiffer sidewall than the Sonic LS/LT’s standard 65 series tires. The Corolla iM’s tires are lower profile than the Sonic’s optional 50 series tires.

For better ride, handling and brake cooling the Corolla iM has standard 17-inch wheels. Smaller 15-inch wheels are standard on the Sonic LS/LT.

Suspension and Handling

For superior ride and handling, the Toyota Corolla iM has fully independent front and rear suspensions. An independent suspension allows the wheels to follow the road at the best angle for gripping the pavement, without compromising ride comfort. The Chevrolet Sonic has a rear torsion beam axle, with a semi-independent rear suspension.

The Corolla iM has standard front and rear stabilizer bars, which help keep the Corolla iM flat and controlled during cornering. The Sonic’s suspension doesn’t offer a rear stabilizer bar.

For a smoother ride and more stable handling, the Corolla iM’s wheelbase is 3 inches longer than on the Sonic (102.4 inches vs. 99.4 inches).

The Corolla iM’s front to rear weight distribution is more even (60.3% to 39.7%) than the Sonic’s (62.5% to 37.5%). This gives the Corolla iM more stable handling and braking.

The Corolla iM handles at .83 G’s, while the Sonic Premier Hatchback pulls only .81 G’s of cornering force in a Car and Driver skidpad test.


For excellent aerodynamics, the Corolla iM has standard flush composite headlights. The Sonic has recessed headlights that spoil its aerodynamic shape and create extra drag.

As tested by Car and Driver, the interior of the Corolla iM is quieter than the Sonic Premier Hatchback:


Corolla iM


At idle

40 dB

41 dB


75 dB

79 dB

70 MPH Cruising

70 dB

71 dB

Cargo Capacity

The Corolla iM has a much larger cargo area than the Sonic Hatchback with its rear seat up (20.8 vs. 19 cubic feet).


The Corolla iM’s standard power windows allow the driver or passenger to lower and raise the windows without leaning over or being distracted. Power windows are only available on the Sonic LT/Premier.

The Corolla iM has a standard locking fuel door with a remote release located convenient to the driver. A locking fuel door helps prevent vandalism, such as sugar in the tank and fuel theft. The Sonic doesn’t offer a locking fuel door.

While driving with high beams on, sensitive light sensors standard on the Corolla iM detect other vehicles which could be blinded and automatically switch to low beams. The Sonic doesn’t offer automatic dimming high beams.

The Corolla iM’s standard outside mirrors include heating elements to clear off the mirrors for better visibility. Chevrolet only offers heated mirrors on the Sonic LT/Premier.

The Corolla iM has a standard center folding armrest for the rear passengers. A center armrest helps make rear passengers more comfortable. The Sonic doesn’t offer a rear seat center armrest.

The Corolla iM’s standard dual zone air conditioning allows the driver and front passenger to choose two completely different temperatures so people with different temperature preferences won’t have to compromise. This makes both the driver and front passenger as comfortable as possible. The Sonic doesn’t offer dual zone air conditioning.

The Corolla iM’s standard automatic temperature control maintains the temperature you set, automatically controlling fan speed, vents and temperature to maintain a consistent, comfortable environment. The Sonic doesn’t offer automatic air conditioning.

For greater rear passenger comfort, the Corolla iM has standard rear heat vents to keep rear occupants more comfortable. The Sonic doesn’t offer rear vents.

The Corolla iM’s available GPS navigation system has a real-time traffic update feature that plots alternative routes to automatically bypass traffic problems. (Service not available in all areas.) The Sonic’s available navigation system doesn’t offer real-time traffic updates.

Economic Advantages

Insurance will cost less for the Corolla iM owner. The Complete Car Cost Guide estimates that insurance for the Corolla iM will cost $5 to $2240 less than the Sonic over a five-year period.

The Corolla iM will cost the buyer less in the long run because of its superior resale value. The IntelliChoice estimates that the Corolla iM will retain 52.2% to 52.56% of its original price after five years, while the Sonic only retains 37.23% to 39.56%.

According to The Car Book by Jack Gillis, the Corolla iM is less expensive to operate than the Sonic because typical repairs cost much less on the Corolla iM than the Sonic, including $67 less for a water pump, $234 less for an alternator, $45 less for front brake pads and $255 less for a power steering pump.

IntelliChoice estimates that five-year ownership costs (depreciation, financing, insurance, fuel, fees, repairs and maintenance) for the Toyota Corolla iM will be $382 to $4980 less than for the Chevrolet Sonic.

© 1991-2018 Advanta-STAR Automotive Research. All rights reserved.

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