Every year, golf club manufacturers come out with new drivers, guaranteed to let you hit the ball longer and straighter. New technology and design trump last year's up-to-the-minute advances. Now I assume that you've finally put that persimmon driver away, but at what point should you be willing to lay out $3-400 for a newer driver than the one you have, and if you want a new driver, should you have to pay that much for it?
Let's look first at the job a driver has to do. It is a club designed to hit the ball off the tee a long way down the fairway. Its bigger head and longer shaft mean that extra distance comes without any extra effort on your part. All you have to do is make sure your swing hits the ball straight, which, because of its relatively upright face, is harder to do with a driver than with any other club.
So before you start looking for a new driver, ask yourself this question. Am I getting everything I need out of the driver I'm using right now? If the answer is yes, I'm getting satisfactory distance and I can put the ball in the fairway consistently, there might not be a reason to switch.
If the answer is no, and you hit all your other clubs just fine, maybe all you need is a lesson to figure out what the problem is. If the answer is you don't hit your other clubs much better either, then it's the singer, not the song, and that $400 would be better spent on lessons.
So it looks like in every case, you should stick with what you have rather than upgrade. Not quite. There are times you should switch. The new designs and technology do make a difference. Maybe not so much from one year to the next, but the improvements compound themselves. If your driver is five years old, advances since it was new could well let you hit significantly better shots, or the same shots more easily.
How would you find out? Go try out some of the new ones under the supervision of your local pro or club fitter. Unless your current driver was fitted when you bought it, you might find that a new driver, fitted to your current swing, makes driving the ball a completely different experience.
Before we leave this subject let me make one more comment. Unless you score in the low 80s, hitting a driver might be the wrong thing to do. This is a difficult club to hit. Unless you are getting your tee shots in the fairway you're losing strokes needlessly.
Higher-handicap golfers would be better served playing a fairway wood or long hybrid (does anybody carry long irons anymore?) off the tee.