If the hybrid battery was in poor condition or even not functioning at all, the car would likely still drive as a normal petrol car, but we would expect this to cause warning lights on the dashboard if it was entirely non-functioning. It would also make it considerably less economical as you would be hauling around the extra weight of the hybrid system without any of the benefits. If you are considering a used example a test drive should show up whether the hybrid battery is functioning, and you could also take the vehicle to a Toyota dealer or independent hybrid/EV specialist who can perform a diagnostic health check.

Hybrid vehicle drive batteries, particularly in Toyotas, tend to have a long lifespan, as they switch in and out during use, unlike the battery in a pure electric vehicle. Toyota has refined and developed its hybrid system over the years to achieve a high level of reliability, evidenced by the number of Prius models that have covered 200,000 miles or more on their original battery.