Reaching for a soft drink to quench your thirst should NOT be an option
I'm sure your smart enough to know that soft drinks are truly not good for you. Soft drinks are among the worst liquids you can drink.  There's nothing beneficial for your body in any way.  Let's, however, go over some key points why soft drinks are to be avoided.

Soft drinks will never quench your body's thirst (and need) for water
Carbonated soft drinks are a diuretic.  Drinking a soft drink will take more water from your system than they will put back in your body.  The digestion process for the high levels of sugar will remove much water from your system.  To replace the water lost from drinking a carbonated soft drink, you will have to drink many glasses of water to make up for your soft drink consumption.

Chemicals found in soft drinks will interfere with digestion
It is possible that the caffeine and sugars shut down the digestion process.

A sugar surplus (and crash) in your body can lead to diabetes
High amounts of sugar in the soft drink can cause your pancreas to produce to much insulin.  Constant elevation and reduction of insulin and sugars in your system can lead to diabetes.

Purified water leaches vital minerals from your body
By its very definition, "purified" water is void of minerals.  By nature, purified water is unnatural and doesn't exit in nature.  Water naturally wants to balance itself with minerals.  Purified water in your system will leach valuable minerals from your system.  Bottled water labeled "Purified Water" is to be avoided.  Also, bottled water which has been labeled "drinking water" is also to be avoided.  "Drinking Water" is labeled such because the FDA has allowed the bottled water companies to include the "Drinking Water" label on water which has been "purified".

Aspartame in "diet" soft drinks has been linked to many diseases
The FDA receives the majority of it's complaints about food additive targeting aspartame.  Diseases involving neurogical complications such as depression have been linked to aspartame.

The chemical "Benzene" found in abundance is linked to leukemia
Eight times the amount of benzene that is allowed in drinking water can be found in carbonated soft drinks. 

Caffeine has been linked to rheumatoid arthritis
What's more, the kidneys are programmed by caffeine to produce excess urine, leading to dehydration.

Phosphates found in soft drinks are nasty
They block absorbtion of calcium and also leach valuable alkaline minerals from the body.

Phosphoric and carbonic acids are found in soft drinks
Acids of a low pH at around 2.5 are 10,000 times more acidic than the desired neutral pH level of 7.0

Oh, Yeah! About fixing your car
Use some Coke on a rag to remove rust from your car bumper.  The police have been know to have coke available to remove blood from the street after an accident.  The delivery driver for Coke use it to clean the engines of their trucks.  To carry Coca-Cola syrup! (the concentrate) the commercial trucks must use a hazardous Material place cards reserved for highly corrosive materials.  The active ingredient in Coke is phosphoric acid. It will dissolve a nail in about four days. Phosphoric acid also leaches calcium from bones and is a major contributor to the rising increase of osteoporosis