If your car blows smoke out from under the hood every time you turn on the engine, or pulls so hard to one side that it's impossible to control when you're driving, then of course it's time to take that vehicle to a mechanic. However, not all signs of needed car repair are quite that obvious; note a few smaller signs that you should be aware of when it comes to your vehicle and its condition so you know to get repairs done as soon as they're needed.
Poor gas mileage
You may have an idea of how often you need to fill your car's gas tank, and it can good to keep track of this, so you know if you're suddenly visiting the pumps more often than usual. Poor fuel economy can mean that your car's exhaust needs repair, as it may not be pulling bad oxygen out of the engine compartment so that you're using more fuel to maintain combustion. The brakes may also not be releasing properly so that the car is experiencing drag; this also causes a vehicle to burn more fuel.
Loss of stopping power
As with gas mileage, you may have a general idea of how quickly and easily you can come to a full stop when you apply the car's brakes. If you find that your car suddenly seems to slide a longer distance when you brake, this can mean a loss of brake fluid or that the pads are severely worn down and not gripping the rotors properly. The tyres could also be worn so that they slide rather than gripping the road. Whatever the cause, this can be very dangerous, and may only get worse over time, so take the car to a mechanic and have the braking system and tyres checked if you notice even a slight loss of stopping power.
The temperature gauge on your dashboard should not typically rise above the mid-level, as the engine's cooling system should always kick in and keep the engine at a moderate temperature even if you're driving very fast or towing something. If the engine does seem to always be running hot, it's good to have this checked, and especially if you've already filled the coolant reservoir tank. The vehicle could have a leak in the radiator or a coolant hose, or may have sediment in the oil reservoir that is causing the engine oil to thicken and not cool as it should.