RC car technology has changed a lot over the years and one of the biggest changes have been batteries. I started with Sanyo SCRC NiCd pack, left the hobby before NiMH came out and came back when LiPo was full swing. Along with brushless power systems, LiPo batteries have revolutionised all RC vehicles - more burst power, higher energy density and multiple cell options. LiPo batteries need a lot of care, more than than a set of nichrome wires that hook your battery pack directly to a car battery anyway. The technology you need to properly charge and care for Lipo (and LiIon batteries) is a balance charger which allows the charger to charge each individual cell at a time rather than all together in series. This is important to not only extend the life and performance of your battery but to minimise the risk of the Lipo pack causing damage to your surroundings.
The right tool for the job
Like everything else to do with RC Cars, LiPo balance chargers are available in any number of models with different features, different interfaces and different quality levels. However unlike, motors, wheels, servos, escs and any other RC car parts they don't wear out and typically the charger you use will be with you for a long time so it is definitely worth having one that does the job properly. With that said you don't need to spend a lot to get a good charger that you can trust with your safety and life of batteries. This is in contrast to charger that come with RTR RC Car kits which at best are inaccurate and at worst are downright dangerous.