It certainly makes sense to have all gasoline engines be capable of running on alcohol fuels. The marginal cost of producing the vehicles is only about $100. The problem lies in the fuel. While Zubrin argues that the U.S. could become completely independent of foreign oil by using alcohol, the reality is far from that simple. Certainly corn ethanol will not get us anywhere near total independence. While cellulosic ethanol holds a lot of promise there are other potential issues. Some of the potential materials that would be used as feed-stocks are currently left on fields and forest floors to decay and replenish the soil. Using those materials to produce fuel would potentially degrade the ability of soils to grow future crops. Using methanol and butanol definitely provide additional fuels that could come from other sources than food crops. Some of Zubrin's arguments seem a bit over-simplified (and don't even get me started on his anti-hydrogen arguments) but the interview is thought-provoking nonetheless.
[Source: Instapundit, thanks to Alex for the tip]