Ford
Flex
Toyota
Sienna
Ford Flex vs Toyota Sienna: 2020 Comparison
The short answer
Based on available data, the Ford Flex comes out ahead of the Toyota Sienna 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
Flex
Overall
Mixed to highly positive among owners, with sentiment heavily dependent on powertrain choice and awareness of a critical, well-known mechanical flaw. Owners express deep affection for the vehicle's unique boxy styling, exceptional passenger comfort across three rows, versatile cargo space, and car-like driving dynamics that avoid the bulkiness of traditional SUVs. The EcoBoost turbocharged V6 engine is frequently praised for strong, satisfying acceleration, making the vehicle a "rocket" or "sleeper." However, this enthusiasm is tempered by a very frequent and severe criticism: the failure-prone internal water pump design on the 3.5L V6 engines (both naturally aspirated and EcoBoost), which can lead to catastrophic engine failure and is described as a matter of "when, not if." Fuel economy is consistently criticized as poor (16-20 MPG combined is typical), exacerbated by a small fuel tank, making it a primary reason owners seek replacements.
Best version to buy
Limited trim with EcoBoost engine and AWD. The Limited trim is associated with premium features like leather, rear climate control, and advanced technology.
Known issues
- ⚠Internal water pump failure: Design flaw where the pump is located inside the engine timing cover; failure can leak coolant into the oil pan, leading to catastrophic engine seizure without obvious external leaks.
- ⚠Poor fuel economy: Real-world combined mileage reported between 16-20 MPG, with a small fuel tank leading to frequent fill-ups. A primary reason owners seek to replace the vehicle. Frequency: very frequent.
- ⚠Rust and corrosion: Significant rust issues reported, particularly on door tops under weather stripping, rear hatch seams, and exhaust components (e.g., "flex pipe"). Frequency: recurrent.
Sienna
Overall
Overwhelmingly positive sentiment regarding long-term reliability, practicality, and fuel efficiency, particularly for the hybrid models (2021+). The Sienna is consistently praised as a durable, low-maintenance family vehicle capable of reaching very high mileages (200,000-300,000+ miles) with proper care. The hybrid powertrain is highlighted as a major advantage, offering significant fuel savings (approximately 36 MPG) compared to competitors.
Best version to buy
For newer generations (2021+), the Platinum trim is frequently recommended for its comprehensive feature set, including ventilated/cooled front seats, a video rearview mirror, and advanced safety technology. The hybrid powertrain is considered non-negotiable for its fuel savings and reliability.
Known issues
- ⚠Transmission problems (2017 models): Jerkiness, shifting issues, high-speed freeway problems, and expired customer service programs for repairs. Frequency: recurrent.
- ⚠Infotainment/system glitches (2025 models): Profile and key fob pairing failures, unresponsive screens. Frequency: isolated.
- ⚠Engine issues (specific older models): Timing chain/crankshaft codes (P001500, P001700) on a brand-new 2025 model; oil/coolant leaks and timing chain failure on a 2015 model. Frequency: isolated.
The verdict
The Ford Flex is the better choice for most buyers.
It has more power on its best-equipped version than the Toyota Sienna, based on the data above. If efficiency matters more to you than outright power, the Toyota Sienna is worth a closer look instead.
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Frequently asked questions
Which is more reliable, the Ford Flex or the Toyota Sienna?
Owner reports show similar reliability sentiment for the Ford Flex and the Toyota Sienna. Check the known issues listed above for specific differences between the two.
Which is better for families, the Ford Flex or the Toyota Sienna?
Both seat a similar number of passengers based on our data. The Ford Flex is classed as a SUV, the Toyota Sienna as a Minivan, which affects cargo space and ride height for family use.
Which has better fuel economy, the Ford Flex or the Toyota Sienna?
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 Ford Flex or the Toyota Sienna?
Exact maintenance costs aren't in our data, but owner reports mention cost-related concerns more often for the Toyota Sienna than the Ford Flex. See the known issues comparison above.