I want to implement a project about a car that detects gold using a metal sensor. The question is, I want the system to save the locations of the gold in a form, maybe an Excel sheet or any form you recommend. how would i connect the GPS with the car, gold detector, and save the locations in somewhere?
how do you plan on detecting gold?
Do you live on a planet where gold is spreads anywhere around? Or what you meant is not a real gold, but the artefact in quest-like game?
Are you treasure hinting or mining?
You might detect a coin but metal detectors don't know if it's a coin or what kind of metal it is. It might give you clue to being ferrous or non-ferrous. It might find a nugget but nuggets are way more rare than gold flakes or gold dust, and it would be even more rare to find one close-enough to the surface to detect.
Of course, all of the "easy gold" has already been found. 
Have you ever seen Gold Rush on the Discovery channel? (It's about mining, not treasure hunting.) One thing you learn is that it's a business with expenses. If they don't mine enough gold to pay for fuel they lose money. Plus the heavy equipment that they have to buy or rent. If they don't own the land they have to lease the mining rights.
The same thing will happen to you... You can drive around all-day, or all year, and you're not going to find enough gold to pay for the gas. 
Would this be a "off road" vehicle, or are you hoping to find gold on paved highways?
I like Gold Rush but /r/prospecting subreddit is probably even more entertaining. There are people there who make the clueless Hoffman family look like geniuses.