Charlotte's Pass and Guthega is a nice drive. Walking from Charlotte's Pass to Kosi, one of the best walks in Oz. Big day though. Chairlift from Thredbo to Top Station is good also.I know its not driving all the way but you can head up to Charlottes Pass & then walk out to Mt. Kosciuszko
Mount Pinnibar via Tom Groggin is a nice drive but it's more like 6 hours return. Have you been in that area before?