It is something quite hard to explain to a mechanic, but if you have felt that sensation, it is best to not ignore it.
The car may just feel unusually difficult to handle. Or maybe, it rides a little more roughly than usual, and it is not as stable. Perhaps there's a vibration that wasn't there before.
Are you experiencing problems steering your car? Are you having problems when you try to steer in a straight line? Your front wheels could need an alignment, or you might have to change some steering parts.
Does your car try to steer, or does it pull to the right or left? You definitely need to find out more if you notice this. It may only be that your tires aren't properly inflated. But, it could as well mean that your friend is damaged or needs alignment. It is not something you want to ignore.
Maybe your car feels like it's vibrating. Your tires may need balancing in this case.
It's a good idea to check your shock absorbers and struts, too. They might need replacing if the car rides "strangely".
If you put on your brakes, and your car pulls to one side - that means you need to take in it for repair.
And most definitely, if the brake pedal goes down excessively, it needs to be checked. You cannot wait to get the car inspected by a technician.
Also scraping and grinding when you brake can indicate problems.
And if your brake light comes on and stays on, bring the car in to be checked immediately, no questions asked.
You might have problems with your engine if you have trouble starting your car. Other indicators include the check engine light coming on, your car using more than one quart of oil between changes, the car engine running after you remove the key, if the car stalls or idles roughly, and if there's poor acceleration. You should also be concerned if you suddenly seem to burn more gas than usual. It could also indicate an engine problem.
Say the word "transmission problems" and your wallet being drained of all that's in it comes to mind. Some of the signs include a slow response when the car is shifted from reverse to drive, if the car doesn't seem to respond when the engine accelerates, or if the car doesn't change gears when you accelerate. If shifting is hard - there could be a problem with transmission, too.
Have your mechanic check it first, to make sure it is not something simple to repair such as a plugged filter or a disconnected hose. It is much easier and less expensive to take care of these kinds of repairs than change a transmission.
Ultimately, you know you car more intimately than anyone else. So, if you feel something is not up to par, it is worth checking it out. You may end up saving money and someone's life!