ALG has put together a model that measures the sensitivity of residual values to increases in gas prices. The associated graph is worth a look, even though ALG's core conclusions are not surprising:

Entry Compacts and Mid Compacts have the largest positive impact to 36-month resale/residual values when gas prices increase. Holding all else constant, when the price of regular gas increases by $1/gallon, Entry Compacts and Mid Compacts experience a lift of 10% and 9%, respectively, to their used values.