Direct pressure measurement systems for auto tires have now set the stage to displace alternative approaches. Tire pressure monitoring systems could soon be a federally legislated requirement, and direct measurement systems provide much improved repeatability. Battery power limits present systems to a life of between seven and 10 years, and future systems will use surface-acoustic-wave (SAW) sensors to eliminate batteries. Direct digital down-conversion permits operation at region-independent 2.45GHz. Companies that have led development of the technology include Schrader Electronics of the United Kingdom, which has systems in mass production. In Germany, a consortium of leading motor makers contracted with Alligator Ventilfabrik and Beru to design a cost-effective TPMS (tire-pressure-monitoring system). A separate effort funded by the information society technology program of the EU has made the Technical Research Centre of Finland the project coordinator for the Apollo consortium. The group's report on intelligent-tiered systems could help save a total of 4,000 lives in Europe each year. Presently, semiconductor vendors are part of a market that will have to supply a semiconductor for every wheel produced in the U.S. Most observers are convinced that the NHTSA's (National Highways Traffic Safety Administration's) direct measurement, four-tire, 20% model will be universally adopted. NHTSA's testing on four original equipment manufacturers (OEMs) fitment indirect systems produced warning thresholds for low-pressure conditions from -8% to -46%, and one system provided no warning at all for pressures as low as 0.98 bar. The agency also noted large differences in response times up to 10 minutes for similar test conditions, as well as unexpected sensitivity to road surface quality between tarmac and loose surfaces. Tests with commercially available TPMS direct systems resulted in an advisory message at an average of a 20% under-inflation level and a safety warning at 36% below recommended pressure. Compared with the indirect approach, the direct technique as drawbacks, including higher installation cost, a limited battery life of five to 10 years, and possible sensor damage when installing replacement tires or when the driver curbs the tire. However, the direct method was shown to be superior in just about all aspects, especially for its ability to reliability report individual tire status.