You will most likely not effect any cost savings IMO because:
1. The alternative fuels market is in growing demand;
2. Aftermarket conversions are therefore probably highly demanded as well;
3. Ethanol is currently needed to replace MTBE as a clean-air additive, so the demand for Ethanol has skyrocketed.
Even if your engine runs ok, your emissions will increase horribly, my guess is from incomplete combustion.
Also ABCesso doesn't list HUMMER as a compatible brand, and I couldn't find the Escalde.
You're probably better off just buying a new Escalade that runs on E85, because the following sounds like a pain in the rectum.
The following is a description of the EPA certification procedure for any gas to alternative fuel conversion:
EPA now certifies converted vehicles, rather than conversion systems or "kits." Typically, EPA refers to a fuels converter (the certificate holder), as a "small volume manufacturer." An individual or entity that wishes to have a vehicle converted to operate on an alternative fuel must do so through a company or organization associated with a certificate holder. Examples of types of companies or organizations that hold Certificates of Conformity issued by EPA include the designer of the conversion equipment, the producer or manufacturer of the equipment, and the person or entity that plans to perform installations. It is the responsibility of the certificate holder to ensure that the equipment is properly installed and that the system is safe, durable, and results in the vehicle meeting the emission standards of the original model year of the vehicle.
Certificates of Conformity for "aftermarket" conversions (conversions on vehicles that are owned by an individual, company, or organization rather than the OEM) are signed by EPA and certify that the appropriate sections of the Code of Federal Regulations (40 CFR Parts 85 through 88) have been met. Certificates indicate the following:
The original test group of vehicles as determined and provided by the OEM. Engine families (since the 2001 model year, light-duty vehicle engine families are known as "test groups") are a subset of vehicles that the OEM certifies and have certain common operating characteristics in terms of emissions control systems. There are many different test groups; for example, the Ford F-150 could have 10 or more test groups, depending on the engine size, gross vehicle weight, and drive train of the vehicle.
The evaporative emissions family.
The state(s) in which the test group is certified (e.g. California vs. 50 state sales areas).
The "car line." For example, "F-150, 2 wheel drive, extended cab, 5.4 Liter engine."
The model year of the vehicles included in the test group.
The emissions standards that are met.
An aftermarket conversion may only be performed on a vehicle if a Certificate of Conformity or a CARB certification has been issued for that vehicle's particular model year and exhaust and evaporative emissions test groups.
For aftermarket AFV conversions, potential certificate holders must complete an application and submit emissions test data to EPA. Each year, certificate holders must file a new application to renew their certificates for a test group of a specific model year, but they do not need to submit new test data in order to renew. For example, for the conversion of a model year 2003 vehicle, EPA can issue a 2004 model year certificate (enabling the certificate holder to convert that model year 2003 vehicle test group through the end of 2004 calendar year) or a 2005 model year certificate (enabling the certificate holder to convert that model year 2003 vehicle through the end of 2005 calendar year). The certificate holder could later apply for a 2006 model year certificate, once EPA begins issuing those certificates (enabling the certificate holder to convert that model year 2003 vehicle test group through end of 2006 calendar year). The certificates are valid through December 31 of each certification year.
EPA Conversions Handbook