the current law denies like-kind trade in treatment for your old auto. you are deemed to have sold it for the trade in value. this value needs to be split between personal and business based on total business mileage over the years to total mileage.
since the personal portion isn't deprecited the potion of the trade-in value allocated to it would result in a personal loss which isn't deductible.
the basis of the new vehicle ignores the trade in value. fo example sales price $5,000 trade in value $3,000 net cash paid $2,000. you basis for the new vehicle is $5,000
