During the early days of the modern hybrid car, a bit of confusion about the technology made it difficult for drivers to know whether or not hybrids were a reliable choice as a vehicle. Some were simply myths or misunderstandings that tended to scare drivers away from hybrid technology, suggesting that hybrid battery packs were liable to fail or that most models couldn't drive fast enough to keep up with traffic on the highway.
Most of these myths have since been debunked. In fact, practically every hybrid-producing car company guarantees its hybrid batteries for the life of the car, so that if there are any problems before a certain mileage is reached, the automaker will replace the battery pack, free of charge. Other assertions, like the claim that hybrid cars are slow, for instance, are based on technological facts -- it's true, hybrids (in general) don't accelerate quite as fast as typical gasoline-powered cars -- but these shortcomings tend to be exaggerated.
Regardless, automotive engineers are continuously making improvements to the technology to make it greener and more efficient. Many hybrid cars are becoming more powerful, primarily due to advances in electric motor technology, without sacrificing too much in the way of overall vehicle fuel economy. Batteries in hybrids are also becoming considerably lighter, which lowers the overall vehicle weight and results in improved efficiency. Not only are they lighter, but they're quickly becoming less expensive and longer lasting, too.