Complex sentence: The new front-wheel drive design in the Tercel, (the first for Toyota) the engine was mounted longitudinally, such that the transmission was mounted under the floorpan, as was standard in a rear-wheel drive car.
Split into simpler sentences: The new front-wheel drive design in the Tercel, unlike their previous front-wheel drive designs, did not have the engine transversely mounted. Rather, the engine was mounted longitudinally, such that the transmission was mounted under the floorpan, as was standard in a rear-wheel drive car.