Natural leather is not on the way out. It still is recognized as the premium material for car seating surfaces, so it remains a "must be available" covering for luxury cars. But in the face of the cost of natural leather and the antagonism of animal activists, it is being forced to share the automotive market, and not just on lower-priced cars.
One artificial leather that offers significant cooling properties when used in car seats is appearing on some new Toyota products, the new RAV4 and Prius V as recent examples. It is a proprietary material called "Softex." When you compare it side-by-side with genuine leather (including perforations if used, and luxury car stitching), there's a lot to like, even to the touch.
"It isn't quite there yet for interiors where we need large foam sections and some really sophisticated graining, as on an Avalon; for those we have other leather-like alternatives," a Toyota spokesman said. "But Softex keeps getting better and I'm sure that in a few years it will be ready for a car like Avalon."
Softex is a thermoplastic polyurethane (TPU). What makes Softex unique is its high breathability and thermal quality. It actually runs cooler because it reflects infrared rays, which is a primary reason for seat-cover heat absorption. In testing, Softex can run up to 10°C (18°F) cooler than other seating materials. The thermal effect is from within the polyurethane layer itself, not a surface treatment.
Although there is some thermal performance variation based on color of the Softex upholstery, Toyota said that even dark colors provide a cooler surface than comparable colors of other artificial leathers.
Cloth and vinyl still are the most widely used "basic" seating materials on lower-priced cars. One characteristic most motorists have learned about vinyl is that in warm, humid weather the passenger's back becomes sweaty and clothing sticks to the seat back. That's because vinyl is nonporous—it doesn't "breathe." And there's a second issue: in time, vinyl can dry out and crack from exposure to sun. Even many natural leather seats eventually may crack, particularly at the bolsters.
Most of the newer artificial leathers in use do "breathe" to some extent, if not as uniformly as natural leather. Softex, for example, absorbs moisture about 15% more slowly than natural leather but releases it more quickly, which is a plus, as in high humidity the passenger's back will feel more comfortable.
Although Softex releases moisture more quickly, so that in effect it dries faster, the material's characteristics are such that, unlike vinyl, it is highly resistant to dry-cracking, according to Toyota. Softex also reportedly has good strength-to-weight and surpasses natural leather in seam fatigue, abrasion, and scratching tests.
The tensile strength of Softex is only slightly lower than natural leather. Although the material does have some limits in forming and sewing some trim patterns (as noted for Avalon, for example), Toyota said it is rated higher in these same areas with other patterns. Toyota added that Softex passes its durability tests, of which a spokesman said "there's a complex battery in a variety of environmental conditions."
Softex, like other artificial leathers, is more resistant to absorbing dirt than natural leather and can more readily be cleaned.
Perhaps Softex' greatest inroad is for the Prius steering wheel covering. In many instances an artificial leather is rated OK for seats, but when it comes to the steering wheel, it has had to be leather for the right feel. This Softex application demonstrates its increasing acceptance; in fact, Toyota promotes the use of the material for seats and steering wheel in its advertising for the Prius V.
"Softex has been well accepted as an advanced leather alternative" by customers, Toyota said, as dealers demonstrate its comparable seat comfort and point to its easier-to-clean properties.