Model-level reading
What changes the warranty calculation
The Chevrolet Impala file contains 6 model years and 626 submitted complaints. The middle year in this set has 85 reports, giving each annual count a model-specific reference point.
2015 has the largest complaint count in the current file at 298. That does not establish a defect rate because sales volume and vehicle age differ across years.
Engine replacement or major internal repair carries the highest midpoint parts estimate among the applicable repair categories at $7,000. I would check whether that system remains under factory coverage before pricing an extra contract.