I think the answer to the first part of your question, the 'major factors in value' is -yes-.
You are correct on the second part about putting a specific percentage. If you are referring to how much traffic one has to deal with to get home and the distance/time to get there, there is an impact. It's probably not studied in the way you want but every buyer takes that under consideration. If I have a buyer who is thinking about buying an extra 1/2 hour away from town because the prices are 20K cheaper, I ask them to figure the cost of transport and the time lost and how that money could be put into a home and family time instead of a gas tank and drive. A person can save close $40k purchasing power by saving $200 in gas. If you are asking this because you are considering where to purchase, I would take a simple formula of $5 per $1,000 of purchase price ($40 = $200) and consider what you want to spend the $200 on - a house or gas. If you value a more rural location and the travel does not bother you and you would be happier, the $200 is better spent on travel expenses.