Starting with 2018, you can't deduct work-related car expenses on your personal tax return unless you have a schedule C business.
Generally speaking, if you lease the car, you can't deduct work-related use starting in 2018. The partnership can reimburse you, but it would be considered part of your taxable income (your draw).
Or, the partnership can lease the car. In that case, any business use is a deduction for the partnership. Any personal use is part of your compensation. So if you drive a "company" leased car 90% for work, the partnership deducts 90% of the car cost as a car expense, and the other 10% is reported as part of your taxable compensation (which is another deduction of course). The 10% personal use represents taxable income to you and you can't deduct any expenses against that 10% income.
