Recapture is a thing for as long as you own the vehicle. You just don't have to do a special section 179 repayment after 5 years. That's 5 years from the in-service date of 12/15/17.
You always pay recapture when you sell depreciated business property. With section 179, the property is fully depreciated so your cost basis is zero. If you sell it for any amount, that amount is taxable capital gain, and is subject to depreciation recapture. For example, if you keep the vehicle 6 years and sell it for $1000, you don't have to worry about the special section 179 rules, but that $1000 is taxable income as depreciation recapture.
