Japan's leading car maker, Toyota Motor Corp., has a new product : It's a super tree with the capacity to absorb 30% more toxic gases from smog than its regular botanical cousin. Toyota is into trees in a big way. Forty researchers have been beavering away in the company laboratory outside Nagoya on the super-tree project. The trees gas-absorbing capacity could eventually help prevent global warming. The company's scientists discovered that by doubling the number of chromosomes in trees they could expand the air inlets on stems and leaves. And the widened inlets sucked up more nitrous oxide.