If you are a W-2 employee you can't deduct any work expenses, that's just the new rules.
If you report your self-employment income on schedule C, you can deduct your car expenses in 1 of 2 different ways.
1. Take the standard mileage deduction of 55 cents per mile. This requires your keep a mileage log or diary of your work mileage. The standard rate includes allowances for gas, maintenance, and wear and tear.
2. Use the actual expense method. You still need a mileage dairy, plus you need accurate records of all your vehicle expenses for the entire year, personal and work. This includes gas, repairs, maintenance, insurance, and depreciation. You deduct a percentage of your total expenses based on the percentage of work miles driven.