Greater vehicle stability, as evidenced by increasing SSF values across vehicle types, occurs both as new make/models enter the market and as previous models are redesigned to appeal to a larger number of consumers. In the first category, perhaps the most noteworthy examples are the crossover vehicles that have been introduced in recent years. These are vehicles that have characteristics of two vehicle types, typically combining aspects of a passenger car with a sport utility vehicle. Examples would be the corporate cousins Ford Escape and Mazda Tribute, both introduced in model year 2001. These vehicles (classified as SUVs in this report) had SSF values of 1.23. The introduction of this new type of vehicle has been beneficial in increasing the SSF of SUVs.

A redesigned vehicle can be compared to its earlier model when SSF values are available for both versions, to note improvements that have occurred. Exhibit 8 presents some examples of passenger cars that increased their SSF values by 0.09 or more as part of a major redesign, while Exhibit 9 contains the same information on LTVs. Note that this report concerns vehicles

Exhibit 8: Passenger Cars Redesigned with Increased SSF

Exhibit 9: LTVs Redesigned with Increased SSF

through model year 2003 only; thus that is the last possible model year listed in the Exhibits. Note also, in some cases what is listed as a redesigned vehicle is actually a successor vehicle, replacing a vehicle the manufacturer stopped producing. For example, the Ford Explorer is the successor to the Ford Bronco II. (There may exist other examples, but these are the ones for which NHTSA has before-and-after SSF test results.)

The previous listed examples are all of consecutive (and for some successor vehicles, concurrent) model year redesigns resulting in increased SSF values. Other examples are available in which an earlier vehicle has a substantially lower SSF than its redesigned counterpart, but SSF data are unavailable for some interim period. For example, the SSF for the 1983-1988 Ford Thunderbird is available. No measurement is available for the redesigned version produced from 1989 through 1997. The Thunderbird was not in production from 1998 through 2001, but in 2002 reappeared on a new platform, having undergone a major overhaul. Exhibits 10 and 11 present, for passenger cars and LTVs, respectively, examples of these interrupted or “long term” increases in SSF.

Exhibit 10: Passenger Cars Redesigned with Long-Term Increased SSF

Exhibit 11: LTVs Redesigned with Long-Term Increased SSF

Of course, not every new vehicle has a higher SSF than those that preceded it. If that were the case, the average SSF would have increased even more sharply than seen in Exhibit 2. The vehicles noted in Exhibits 8 through 11 are presented as some outstanding examples of passenger cars and LTVs that have been redesigned and/or succeeded by vehicles offering substantially improved stability.

As seen in this report, vehicles today are considerably improved with respect to stability as compared to those of the past, particularly in the case of sport utility vehicles. By providing information on SSF, NHTSA has enabled the consumer to make a better-informed purchase. Given the lead time necessary to introduce a new vehicle or redesign an existing vehicle extensively enough to alter its SSF, it is unlikely that market incentives begun in model year 2001 (when NCAP consumer rollover ratings were first available) could have influenced SSF values by model year 2003. However, it seems that by model year 2003, both manufacturers and consumers were in agreement of the need for greater stability in passenger vehicles. Examining trends in SSF over an even longer period of time would enable a more definitive statement on the impact that published NCAP information has had. However, the evidence suggests that manufacturers are responding to the marketplace and incorporating desirable changes into the new vehicle fleet.