By John Voelcker IEEE Spectrum Your mileage may vary Yes indeed t could be as much as 30 percent lower than government ratings as some new owners of hybrid electric vehicles discovered to their dismay last year If 2004 began with drivers in the United States and a few other places giving hybrids a heartfelt hug it ended with a more subdued embrace One of the reasons was disappointment over real world mileage Official ratings for fuel use based on the outdated driving patterns of U S government tests turned out to be a poor predictor for what typical buyers could expect But if the hybrid honeymoon is over the marriage is still in solid shape In some areas a buyer must wait months for a Toyota Prius Toyota plans to build 100 000 Priuses in 2005 up from 67 000 last year Waiting in the wings is the Lexus RH 400h luxury hybrid sport utility vehicle now scheduled to go on sale 15 April in the United States As of December 2004 buyers had already paid deposits for half of the year s production of 20 000 Hybrids are now also offered or planned by Ford General Motors Honda Nissan and Toyota GM and DaimlerChrysler announced that they would get together to develop a full hybrid system to be offered in the 2008 model year Even Porsche confirmed that it might license Toyota s hybrid technology for its sport utility Cayenne infuriating die hard fans of the company s signature lithe high performance sports cars Still though hybrids are hot no single vehicle is likely to make as much of a splash this year as the revamped Prius did in 2004 The closest thing to a recurring theme in 2005 will be electronic stability control It will shift from an expensive option to a necessity on the tall heavy sport utility vehicles that still make up one of the most popular categories in the United States Daimler Ford and GM announced that stability control would be standard on all their SUVs by the 2007 model year The notice followed the release of a study by the U S National Highway Traffic Safety Admi