Kia
Optima
Mazda
6
Kia Optima vs Mazda 6: 2018 Comparison
The short answer
Based on available data, the Kia Optima comes out ahead of the Mazda 6 on power. Check the specs table and owner sentiment below for the full comparison before deciding between the two. Both are covered by real owner reports on CarWizz.
Specs side by side
What owners say
Optima
Overall
Mixed sentiment with a strong generational divide. Long-term owners of earlier models (pre-2011) report exceptionally high reliability and satisfaction, with examples reaching over 270,000 miles with minimal maintenance beyond oil changes. For the 2011-2019 generation, sentiment is sharply split.
Best version to buy
Insufficient owner data available to declare a consensus "best" trim or powertrain. Feedback is contradictory: some owners strongly recommend the V6 engine (available in earlier models) for its bulletproof reliability compared to the problematic four-cylinders, while others praise the top-tier SXL Turbo trim for its features and driving experience despite the inherent engine risk.
Known issues
- ⚠Catastrophic engine failure (Theta II 2.4L/2.0T): Connecting rod bearing failure leading to seized engine, often around 100,000-150,000 miles; also severe oil consumption.
- ⚠Excessive oil consumption: Engine burns oil at a high rate, potentially leading to damage if not monitored closely. Frequency: recurrent.
- ⚠Engine replacement process hardships: Long repair times (weeks to months), difficulties with dealer service departments, out-of-pocket costs for rental cars and misdiagnoses despite warranty coverage. Frequency: recurrent.
6
Overall
Sentiment is broadly positive, with the Mazda 6 consistently praised for its reliability, longevity, and driving dynamics. Long-term owner reports frequently highlight the vehicle's ability to reach high mileages (e.g., 250,000 miles, 377,000 miles) with minimal major issues when properly maintained. The car is commended for its handsome design, well-regarded interior quality in its class, and a driving experience often described as more engaging than key competitors like the Toyota Camry and Honda Accord.
Best version to buy
Insufficient owner data available to declare a single "best" trim or version across all generations. Feedback is divided by powertrain preference.
Known issues
- ⚠Thin paint / paint chipping and fading: noted on multiple generations, particularly older models. Frequency: recurrent.
- ⚠Rust issues: especially on heat shields and exhaust components, causing rattles; mentioned on pre-2014 models and some later examples. Frequency: recurrent.
- ⚠Steering wheel vibration / shake at highway speeds (55-65 mph / 89-105 km/h): often attributed to tire balance rather than mechanical fault. Frequency: isolated.
The verdict
The Kia Optima is the better choice for most buyers.
It has more power on its best-equipped version than the Mazda 6, based on the data above. If efficiency matters more to you than outright power, the Mazda 6 is worth a closer look instead.
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Frequently asked questions
Which is more reliable, the Kia Optima or the Mazda 6?
Owner reports show similar reliability sentiment for the Kia Optima and the Mazda 6. Check the known issues listed above for specific differences between the two.
Which is better for families, the Kia Optima or the Mazda 6?
Data on family-specific factors like cargo space is limited for one or both models, but based on available reports, both are positioned as practical daily drivers. Check the specs table above for seating and body type.
Which has better fuel economy, the Kia Optima or the Mazda 6?
Fuel consumption data is limited for one or both models. Check the specs table above for the figures available on each catalogued version.
Which is cheaper to maintain, the Kia Optima or the Mazda 6?
Exact maintenance costs aren't in our data, but owner reports mention cost-related concerns more often for the Mazda 6 than the Kia Optima. See the known issues comparison above.