Compare the2025 Kia K4VS 2025 Honda Civic Si

Safety
Warranty
Reliability
Fuel Economy and Range
Environmental Friendliness
Transmission
Tires and Wheels
Suspension and Handling
Passenger Space
Cargo Capacity
Ergonomics

Safety

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With its standard Forward Collision-Avoidance Assist, the Kia K4 is better at preventing collisions with pedestrians than the Honda Civic Si, according to the Insurance Institute for Highway Safety:

	K4	Civic Si
Overall Evaluation	GOOD	ACCEPTABLE
	Crossing Child - DAY
12 MPH	AVOIDED	AVOIDED
	Crossing Adult - NIGHT
12 MPH Brights	AVOIDED	AVOIDED
12 MPH Low beams	AVOIDED	-10 MPH
25 MPH Brights	AVOIDED	-22 MPH
	Parallel Adult - NIGHT
25 MPH Brights	AVOIDED	AVOIDED
25 MPH Low beams	AVOIDED	AVOIDED
37 MPH Brights	AVOIDED	AVOIDED
37 MPH Low beams	AVOIDED	-18 MPH
Warning Issued-Low beams	1.5 sec	1.1 sec

In a Vehicle-to-Vehicle Frontal Crash Prevention 2.0 test conducted by the Insurance Institute for Highway Safety (IIHS), the Kia K4 achieved a “Acceptable” rating - the second highest possible - for its performance in forward collision warning and automatic braking systems, demonstrating its excellent capabilities in preventing collisions. The Honda Civic Si has not been tested.

Over 200 people are killed each year when backed over by motor vehicles. The K4 GT-Line Turbo offers optional Reverse Parking Collision-Avoidance Assist that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The Civic Si doesn’t offer backup collision prevention brakes.

The K4 GT-Line Turbo offers an optional Surround View Monitor to allow the driver to see objects all around the vehicle on a screen. The Civic Si only offers a rear monitor.

Both the K4 and Civic Si have rear cross-traffic warning, but the K4 LXS/EX/GT-Line has Rear Cross-Traffic Collision-Avoidance Assist (automatically applies the brakes) to better prevent a collision when backing near traffic. The Civic Si’s Rear Cross Traffic Monitor doesn’t automatically brake.

Both the K4 and the Civic Si have standard driver and passenger frontal airbags, front and rear side-impact airbags, side-impact head airbags, front and rear seatbelt pretensioners, front wheel drive, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, rearview cameras, driver alert monitors and available blind spot warning systems.

The National Highway Traffic Safety Administration does 35 MPH front crash tests on new vehicles. In this test, results indicate that the Kia K4 is safer than the Honda Civic Si:

	K4	Civic Si
	Driver
STARS	5 Stars	5 Stars
Neck Injury Risk	16.7%	30%
Neck Stress	129 lbs.	241 lbs.
Leg Forces (l/r)	147/158 lbs.	189/372 lbs.
	Passenger
STARS	4 Stars	4 Stars
HIC	349	444
Neck Stress	118 lbs.	189 lbs.
Leg Forces (l/r)	315/48 lbs.	275/164 lbs.

New test not comparable to pre-2011 test results. More stars = Better. Lower test results = Better.

The Insurance Institute for Highway Safety does 40 MPH moderate front offset crash tests on new cars. In this updated test, results indicate that the K4 is safer than the Civic Si:

	K4	Civic Si
Overall Evaluation	GOOD	ACCEPTABLE
Structure	GOOD	GOOD
	Driver Injury Measures
Head/Neck Rating	GOOD	GOOD
Head Injury Criterion	168	377
Chest Rating	GOOD	GOOD
Thigh/hip Rating	GOOD	GOOD
Leg/foot Rating	GOOD	GOOD
Leg Forces L/R	405/382 pounds	607/495 pounds
Restraints	GOOD	GOOD
	Rear Passenger Injury Measures
Head/Neck Rating	GOOD	GOOD
Thigh Rating	GOOD	GOOD
Restraints	GOOD	MARGINAL

The National Highway Traffic Safety Administration does side impact tests on new vehicles. In this test, which crashes the vehicle into a flat barrier at 38.5 MPH and into a post at 20 MPH, results indicate that the Kia K4 is safer than the Honda Civic Si:

	K4	Civic Si
	Front Seat
STARS	5 Stars	5 Stars
Abdominal Force	196 lbs.	286 lbs.
	Rear Seat
STARS	5 Stars	5 Stars
Spine Acceleration	66 G’s	79 G’s
	Into Pole
STARS	5 Stars	5 Stars
Max Damage Depth	11 inches	12 inches
HIC	178	260
Spine Acceleration	42 G’s	51 G’s
Hip Force	693 lbs.	805 lbs.

New test not comparable to pre-2011 test results. More stars = Better. Lower test results = Better.

The Kia K4 (Built after January 2025) has achieved the Insurance Institute for Highway Safety’s (IIHS) highest rating of “Top Safety Pick Plus” for the 2025 model year. This distinction is based on its exceptional performance in IIHS’ rigorous battery of safety tests. Specifically, it earned a “Good” rating in the latest, more stringent moderate overlap front crash test, a “Good” result in the updated side impact test, and a “Good” score in the revised pedestrian crash prevention test. The Civic Si is only a standard “Top Safety Pick” for 2025.

Warranty

The K4 comes with a full 5-year/60,000-mile basic warranty, which covers the entire car and includes 24-hour roadside assistance. The Civic Si’s 3-year/36,000-mile basic warranty expires 2 years or 24,000 miles sooner.

Kia’s powertrain warranty covers the K4 5 years and 40,000 miles longer than Honda covers the Civic Si. Any repair needed on the engine, transmission, axles, joints or driveshafts is fully covered for 10 years or 100,000 miles. Coverage on the Civic Si ends after only 5 years or 60,000 miles.

Reliability

J.D. Power and Associates’ 2024 Initial Quality Study of new car owners surveyed provide the statistics that show that Kia vehicles are better in initial quality than Honda vehicles. J.D. Power ranks Kia fourth in initial quality, above the industry average. With 18 more problems per 100 vehicles, Honda is ranked 10th.

J.D. Power and Associates’ 2024 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Kia vehicles are more reliable than Honda vehicles. J.D. Power ranks Kia above average in long-term dependability. With 3 more problems per 100 vehicles in the first three years of ownership, Honda is rated below average.

Fuel Economy and Range

On the EPA test cycle the K4 gets better mileage than the Civic Si:

		MPG
K4
	LX 2.0 DOHC 4-cyl.	30 city/40 hwy
	2.0 DOHC 4-cyl.	29 city/39 hwy
Civic Si
	1.5 turbo 4-cyl.	27 city/37 hwy

To lower fuel costs and make buying fuel easier, the Kia K4 uses regular unleaded gasoline. The Civic Si requires premium for maximum efficiency, which can cost on average about 84.9 cents more per gallon.

Environmental Friendliness

In its Green Vehicle Guide, the U.S. Environmental Protection Agency (EPA) rates the Kia K4 higher (6 out of 10) than the Honda Civic Si (5). This means the K4 produces up to 6.9 pounds less smog-producing pollutants than the Civic Si every 15,000 miles.

Transmission

The K4 offers an optional automatic transmission, for driver comfort, especially in the city. The Civic Si doesn’t offer an automatic transmission.

The K4 has a standard 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 Civic Si doesn’t offer a CVT.

Tires and Wheels

The K4 has a standard space-saver spare tire so you can replace a flat tire and drive to have the flat repaired or replaced. A spare tire isn’t available on the Civic Si; it requires you to depend on roadside assistance and your vehicle will have to be towed.

Suspension and Handling

For better handling and stability, the average track (width between the wheels) on the K4 is 1.6 inches wider in the front and .8 inches wider in the rear than the track on the Civic Si.

For better maneuverability, the K4’s turning circle is 2.9 feet tighter than the Civic Si’s (35.2 feet vs. 38.1 feet).

Passenger Space

The K4 has 2.1 cubic feet more passenger volume than the Civic Si (98.7 vs. 96.6).

The K4 has 1.4 inches more front headroom, .2 inches more rear headroom, .6 inches more rear legroom and 3 inches more rear hip room than the Civic Si.

Cargo Capacity

The K4 has a larger trunk than the Civic Si (14.6 vs. 14.1 cubic feet).

To make loading groceries and cargo easier when your hands are full, the K4’s trunk can be opened just by waiting momentarily behind the back bumper, leaving your hands completely free. The Civic Si doesn’t offer a hands-free gesture to open its trunk, forcing you to put cargo down if your hands are full.

Ergonomics

When two different drivers share the K4 GT-Line, the optional memory seats and mirrors make it convenient for both. Each setting activates different, customized memories for the driver’s seat position and outside mirror angle. The Civic Si doesn’t offer a memory system.

The K4 GT-Line’s optional easy entry system glides the driver’s seat back when the door is unlocked or the ignition is switched off, making it easier for the driver to get in and out. The Civic Si doesn’t offer an easy entry system.

The power windows standard on both the K4 and the Civic Si have locks to prevent small children from operating them. When the lock on the K4 is engaged the driver can still operate all of the windows, for instance to close one opened by a child. The Civic Si prevents the driver from operating the other windows just as it does the other passengers.

When the K4 GT-Line with available tilt-down mirrors is put in reverse, both rearview mirrors tilt from their original position. This gives the driver a better view of the curb during parallel parking maneuvers. Shifting out of reverse puts the mirrors into their original positions. The Civic Si’s mirrors don’t automatically adjust for backing.

The K4’s optional rear view mirror has an automatic dimming feature. This mirror can be set to automatically darken quickly when headlights shine on it, keeping following vehicles from blinding or distracting the driver. The Civic Si doesn’t offer the luxury of an automatic dimming rear view mirror.

Optional air-conditioned seats in the K4 GT-Line keep the driver and front passenger comfortable and take the sting out of hot seats in Summer. The Civic Si doesn’t offer air-conditioned seats.

The K4 EX/GT-Line’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 Civic Si doesn’t offer dual zone air conditioning.

Both the K4 and the Civic Si offer rear vents. For greater rear passenger comfort, the K4 GT-Line Turbo has standard rear air conditioning vents to keep rear occupants cool in summer or warm in winter. The Civic Si doesn’t offer rear air conditioning vents, only heat vents.

Compared to the Honda Civic Si, the Kia K4 eliminates the need for separate garage door openers and associated risks of losing, breaking, or having dead batteries with its optional integrated Homelink® universal remote controlled from the rear view mirror.

To quickly and conveniently keep personal devices charged without cables tangling and wearing out, the Kia K4 EX/GT-Line has a standard wireless phone charging system (Qi) in the front center console. The Civic Si doesn’t offer wireless personal charging.

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