Use W and S to increase or decrease your acceleration, or the numbad to choose a percentage.
W will increase your acceleration, while S will decrease it or put you in reverse. The throttle indicator on the left next to your paperdoll shows how fast you are currently, and each line represents a percentage. If you want an exact percentage for your speed, you can use the numeric keypad to select one. It works as you might expect: one for ten percent, two for twenty percent, etc. You can use them to set a speed you're comfortable with during a fight, allowing you to focus on your movements, your legs, and your goal.
That said, you can also press the Add key on the numeric keypad to activate Throttle Decay. This means that your throttle - your speed - will automatically decrease to zero after releasing the W key. This can be useful for quick adjustments, but it may take some time for new players to adjust, as you have to put your throttle on. feathered to maintain the desired speed.
Additionally, you can press G to go at the current rate of your lance, although this tends to be at maximum acceleration. Use it to follow your lance, since maximizing your throttle is fairly easy to do with W. Remember that your speed will decrease when you enter something you can't plow, but turning will increase l 'accelerator to where it was. The same goes for walking through things - you'll slow down as you walk through a building, but you won't need to revert to your previous speed once you've walked through it.
And here's how to control your speed in MechWarrior 5. For more guides, be sure to keep an eye on our guides page.