Compare the2025 Kia K5VS 2024 Lexus IS

Both the K5 and IS have child safety locks to prevent children from opening the rear doors. The K5 has power child safety locks, allowing the driver to activate and deactivate them from the driver's seat and to know when they're engaged. The IS’ child locks have to be individually engaged at each rear door with a manual switch. The driver can’t know the status of the locks without opening the doors and checking them.

In the past twenty years hundreds of infants and young children have died after being left in vehicles, usually by accident. When turning the vehicle off, drivers of the K5 are reminded to check the back seat if they opened the rear door before starting out. The IS doesn’t offer a back seat reminder.

To help make backing out of a parking space safer, the K5 has standard Rear Cross-Traffic Collision Warning with Rear Cross-Traffic Collision-Avoidance Assist, systems which detect vehicles approaching from the sides and can automatically apply the brakes to prevent a collision. Rear Cross-Traffic Braking costs extra on the IS.

The K5’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 IS doesn’t offer a driver alert monitor.

Both the K5 and the IS have standard driver and passenger frontal airbags, front and rear side-impact airbags, driver knee airbags, side-impact head airbags, front seatbelt pretensioners, height adjustable front shoulder belts, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, lane departure warning systems, blind spot warning systems, rearview cameras, rear cross-path warning and available around view monitors.

The K5 comes with a full 5-year/60,000-mile basic warranty, which covers the entire car and includes 24-hour roadside assistance. The IS’ 4-year/50,000-mile basic warranty expires 1 year or 10,000 miles sooner.

Kia’s powertrain warranty covers the K5 4 years and 30,000 miles longer than Lexus covers the IS. Any repair needed on the engine, transmission, axles, joints or driveshafts is fully covered for 10 years or 100,000 miles. Coverage on the IS ends after only 6 years or 70,000 miles.

There are over 3 times as many Kia dealers as there are Lexus dealers, which makes it much easier should you ever need service under the K5’s warranty.

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 Lexus vehicles. J.D. Power ranks Kia fourth in initial quality, above the industry average. With 11 more problems per 100 vehicles, Lexus is ranked 8th.

As tested in Motor Trend the K5 GT 2.5 turbo 4-cylinder is faster than the Lexus IS:

On the EPA test cycle the K5 gets better mileage than the IS:

In heavy traffic or at stoplights the K5 LX’s engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. The engine is automatically restarted when the driver gets ready to move again. The IS doesn’t offer an automatic engine start/stop system.

To lower fuel costs and make buying fuel easier, the Kia K5 uses regular unleaded gasoline. The IS requires premium, which can cost on average about 82.8 cents more per gallon.

The K5 offers an available sequential manual gearbox (SMG). With no clutch pedal to worry about and a fully automatic mode, an SMG is much more efficient than a conventional automatic but just as easy to drive. The IS doesn’t offer an SMG or a conventional manual transmission.

The K5 GT’s launch control uses engine electronics to hold engine RPM’s precisely in order to provide the most stable and rapid acceleration possible, using all of the available traction. The IS doesn’t offer launch control.

For better traction, the K5 GT’s tires are larger than the largest tires available on the IS (245/40R19 vs. 235/40R19).

The K5 has standard front and rear gas-charged shocks for better control over choppy roads. The IS base model’s suspension doesn’t offer gas-charged shocks.

For a smoother ride and more stable handling, the K5’s wheelbase is 2 inches longer than on the IS (112.2 inches vs. 110.2 inches).

For better handling and stability, the average track (width between the wheels) on the K5 is 1.6 inches wider in the front and 1.5 inches wider in the rear than the average track on the IS.

The Kia K5 may be more efficient, handle and accelerate better because it weighs about 300 to 500 pounds less than the Lexus IS.

The design of the Kia K5 amounts to more than styling. The K5 has an aerodynamic coefficient of drag of .27 Cd. That is lower than the IS (.28 to .3) and many sports cars. A more efficient exterior helps keep the interior quieter and helps the K5 get better fuel mileage.

Because it has more passenger and cargo room, the EPA rates the K5 a Large car, while the IS is rated a Compact.

The K5 has 15.1 cubic feet more passenger volume than the IS (105.3 vs. 90.2).

The K5 has 2 inches more front headroom, 1.3 inches more front legroom, 2.3 inches more front hip room, 2.1 inches more front shoulder room, .9 inches more rear headroom, 3 inches more rear legroom, 2.6 inches more rear hip room and 2.7 inches more rear shoulder room than the IS.

The K5 has a much larger trunk than the IS (15.6 vs. 10.8 cubic feet).

To make loading groceries and cargo easier when your hands are full, the K5’s trunk can be opened just by waiting momentarily behind the back bumper, leaving your hands completely free. The IS doesn’t offer a hands-free gesture to open its trunk, forcing you to put cargo down if your hands are full.

The power windows standard on both the K5 and the IS have locks to prevent small children from operating them. When the lock on the K5 is engaged the driver can still operate all of the windows, for instance to close one opened by a child. The IS prevents the driver from operating the other windows just as it does the other passengers.

The K5’s power window, power lock, power mirror and cruise control switches are lit from behind, making them plainly visible and easier to operate at night. The IS’ cruise control switches are unlit, making them difficult to find at night and operate safely.

To shield the driver and front passenger’s vision over a larger portion of the windshield and side windows, the K5 has standard extendable sun visors. The IS doesn’t offer extendable visors.

To quickly and conveniently keep personal devices charged without cables tangling and wearing out, the Kia K5 GT-Line/EX/GT has a standard wireless phone charging system (Qi) in the front center console. The IS doesn’t offer wireless personal charging.

The Kia K5 outsold the Lexus IS by almost three to one during 2023.