I own a pretty decent Fluke and last fall I had a car battery crap out so I decided to do a comparison. I read the battery with the Fluke and then tried several of the "Freebie" Harbor Freight (
https://www.harborfreight.com/7-function-multimeter-98025.html) ones that I have accumulated over the years for comparison.
To my amazement they all were within 2 to 3% of each other's readings.
As an aside, the only real way to accurately test a car battery is with a load tester.