Grades: 2 - 4 Technology is catching up to science fiction with extreme machines, as you’ll read about in this fast-paced series. Some of the world’s fastest & dirtiest extreme vehicles are explored in these titles. Accelerated Reader® titles, RL: 3.4-3.7. Guided reading levels: M-N. Lexile levels: 680L-760L. Paperback, 32 pages each.