Section 1To be clear, Japanese automakers still build many of the most dependable vehicles on the road. Toyota, Honda, Lexus, Subaru, and Mazda continue to perform well in long-term reliability studies.But as this list shows, a familiar badge doesn't guarantee bulletproof reliability.5. Infiniti QX80Infiniti completely redesigned the QX80 for 2025, replacing its long-running naturally aspirated 5.6-liter V8 with a new twin-turbocharged V6. The new engine delivers better power and efficiency, but reliability concerns are already surfacing.J.D. Power currently gives the QX80 a “Fair” quality and reliability rating of 66 out of 100, and both the 2025 and 2026 model years have already been hit with multiple recalls.The outgoing V8-powered QX80 wasn’t modern, but it earned a reputation for durability over time.4. Toyota TundraThe current-generation Tundra has struggled with several high-profile issues since its launch.Toyota replaced the old V8 with a twin-turbo 3.4-liter V6 and introduced the hybrid i-Force Max setup for the latest Tundra. While performance improved significantly, reliability doesn't live up to Toyota’s usual standards. Consumer Reports currently gives the 2026 Tundra a predicted reliability score of 41 out of 100.The truck has also been tied to multiple recalls, including ongoing concerns involving engine machining debris that could lead to catastrophic failures.3. Acura ZDXHonda’s partnership with General Motors to develop EVs hasn’t gone smoothly, and the Acura ZDX is proof of that.To be fair, the ZDX isn't truly a Japanese car; it's actually built by GM alongside the Chevrolet Blazer EV and Cadillac Lyriq. The ZDX has faced software bugs, electrical glitches, and recall issues almost immediately after launch. Consumer Reports gives the electric SUV a predicted reliability score of just 39 out of 100.Acura has already discontinued the ZDX after only a short production run.2. Honda PrologueUnfortunately for Honda, the Prologue shares many of the same problems as the Acura ZDX because underneath, they’re the same.Also riding on GM’s Ultium architecture, the Prologue has struggled with electronics, charging systems, climate controls, and overall build quality. Consumer Reports currently assigns it a predicted reliability score of just 25 out of 100, making it one of the lowest-rated Hondas in recent memory.1. Mazda CX-90 PHEVThe Mazda CX-90 Plug-In Hybrid rounds out the list with the worst reliability score of the group.Mazda’s new flagship SUV has earned praise for its upscale interior, strong driving dynamics, and premium feel, but the plug-in hybrid system has generated tons of complaints. Consumer Reports currently gives the CX-90 PHEV a predicted reliability score of just 20 out of 100.Owners have reported problems involving the battery system, drivetrain electronics, and hybrid powertrain operation. Even the standard gas-powered CX-90 hasn’t been completely immune to issues, scoring only slightly better overall.