Toyota already makes a diesel version of the Tacoma (known as the Hilux). The Hilux offers two turbocharged diesel engine options. These vehicles get 30-35 mpg, can tow 5,000lbs., and will last 300,000+ miles. If you want it in the U.S., then go to the Toyota website and contact them, via email, and request it. Let them know you want the Hilux (with the diesel option) available in the U.S. as soon as possible. I contacted Toyota and they said they are considering bringing the Hilux to the U.S., but were gauging customer demand. Each customer's request is given a file number and is cataloged. When enough people demand the Hilux in the U.S., they will make it available. So now is the time to let them know what you think!
P.S. Just google "2009 Toyota Hilux Euro Spec" if you want to see the Hilux already available in Europe. The Hilux is a far superior vehicle than the Tacoma we are stuck with in the U.S.