Driving a car that doesn't accelerate like it should is not just annoying but potentially dangerous. You don't want to be struggling to go uphill in a sluggish vehicle, nor do you want to fail to reach the proper speed when you're merging onto a highway. There are several reasons why your vehicle isn't accelerating properly. While some of those are signs that you have more severe problems with your car, others are relatively easy to diagnose and repair. We're going to take a look at four of the more common reasons for a sluggish vehicle and what you can do to fix them.