You will want to look at "Transportation" on page 14 in IRS Pub 502.
The important phrase is "You can include in medical expenses amounts paid for transportation primarily for, and essential to, medical care."
I don't think that the IRS would think that going to a grocery store is "medical care". I might think differently if you were the sole caregiver for a dependent in a wheelchair who you had to keep with you when you did grocery shopping, but I don't know enough abut your situation to hazard a guess.
On the other hand, if you needed to rent the specially-modified van to go to medical appointments (doctor visits, PT, tests, etc.), then this would clearly be allowable. So could you deduct the expenses if you stopped by the grocery store on the way home from a necessary medical visit? You could make that argument, but you should keep very good records in that case.
You will want to look at "Transportation" on page 14 in IRS Pub 502.
The important phrase is "You can include in medical expenses amounts paid for transportation primarily for, and essential to, medical care."
I don't think that the IRS would think that going to a grocery store is "medical care". I might think differently if you were the sole caregiver for a dependent in a wheelchair who you had to keep with you when you did grocery shopping, but I don't know enough abut your situation to hazard a guess.
On the other hand, if you needed to rent the specially-modified van to go to medical appointments (doctor visits, PT, tests, etc.), then this would clearly be allowable. So could you deduct the expenses if you stopped by the grocery store on the way home from a necessary medical visit? You could make that argument, but you should keep very good records in that case.