Performance
Regarding horsepower, the Kia Optima packs quite a punch and will knock the Toyota down a few rungs. However, bear in mind that high horsepower engines often command higher insurance premiums.
Handling
With their similar turning circles, the Kia and the Toyota Corolla definitely handle about the same into and out of tight spots.
Drivetrain
The Toyota Corolla's engine is considerably smaller than the Kia Optima's. Note that smaller engines can be stressed more; on the flip side, smaller engines typically get better gas mileage.
Torque equals pickup, and the Kia Optima will have picked up and gone by the time the Corolla finally gets moving.
The Toyota could learn a lesson or two from the Kia Optima as far as torque.
Utility
The Kia Optima and the Toyota can accommodate the same number of passengers.
Convenience
You'll most definitely take the Toyota Corolla for a fill-up about as often as the Kia Optima.
Comfort
Taller drivers will considerably enjoy the extra head room in the Kia's front cabin compared to the Toyota.
The ampler interior dimensions of the Kia Optima make it significantly more spacious for your passengers than the Toyota Corolla.
Dimensions
The Kia Optima is tremendously more bulky than the Toyota Corolla.
Your wallet will hurt more every time you fill up the Kia Optima than the Toyota Corolla because of its bigger tank.
The Toyota Corolla and the Kia Optima compete for the same parking spaces.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs approximately the same to get the Kia to the dealership as the Toyota Corolla.
The Optima pales in comparison to the Toyota Corolla with respect to gas mileage.
The Kia won't tax your gasoline budget substantially more than the Toyota Corolla will.
The Kia is considerably pricier than the Toyota Corolla as far as MSRP.
Warranty
The basic warranty that comes with the Toyota Corolla isn't quite as generous as the Optima's.