ALG, the industry benchmark for residual values and depreciation data, www.alg.com. Full-size car category. ALG Residual Percentage Guide, 2009-2012. Residual value is the value of the Vehicle at the end of the Lease used in calculating your base monthly payment. Residual value has no impact on the resale or trade-in value of a vehicle. ALG uses an econometric model to predict residual value and considers many factors including pricing (including MSRP), incentives, vehicle characteristics, market trends and economic variables.