2012 hyundai elantra touring gls at; test parameters: under my normal, consistent, everyday driving circumstances- i'm a delivery driver subcontractor; raw numbers: filled up at 41,052 miles and again at 41,417 miles driving 365 miles; 33.3mpg for this one tankful; the same gas pump was used at the same gas station, filling the car to the same level, as close as possible;the mpg was calculated by hand using simple arithmetic; again, it was one and only one tankful; this drive was 70% highway and 30% city; top-tier 87 octane gas was used; it was 84 degreesF with little or no wind... this was my third tankful after changing to this oil; the first two tankfuls were 29 mpg and 31 mpg, respectfully; it is my educated guess that my mpg will level off at 5 to 7% improvement; ff rl 0w20 35mpg hypermileage; 15k to 39.5k: pp 5w20, chevron synthetic 5w 20, and gtx hm/ syn blend blend 5w20 all 30 mpg; possible sources of variation are number of gallons of gasoline used to fill up the car and unusually favorable driving conditions (less traffic, more freeway driving and optimum speeds.)