The way I read it and how my brother in law (who is a CPA and has helped his dad with their family business) read it is that the standard mileage deduction is in regards to ANYTHING that goes into or onto the car. Gas, Oil, Maintenance, Tint, Car Washes, etc all go along with the standard deduction.
THIS is why its very very important to keep a VERY detailed list of your expenses, sometimes its not best to use the standard deduction but if you don't you'd be better off getting a CPA or knowing the rules very very well. Some folks on here have said that they don't move their cars unless they are driving for a rideshare program so it would behoove them not to take the standard deduction.
In regards to meals (water/snacks) as long as it's given for the purpose of conducting business you're good. Like Steve said a percentage of your cell phone bill can go towards it.
Be forewarned that the forms and websites will normally NOT limit you on what you can enter for deductions so you must make sure your information is correct. The only real weird part that doesn't seem to be written in black and white is when your miles are able to be claimed. For example I like driving downtown Dallas or the Airport but they are over an hour away, and how we interpret it it can be said that from the moment I leave my house going towards work those miles count. Some folks say they count the miles home once done, this is still what I'm figuring out. That being said I am a spreadsheet/data ***** and keep very detailed records so I could easily add or remove that information as needed (thank you google sheets!)
Hope that helped! Also NEVER rely completely on tax information from anyone but a professional, that being said even IRS folks get it wrong.