There's not enough information to answer that question. If you're going any great distance, riding in low gear with high RPM is going to use more gas. More revolutions = more vacuum = more gas consumed. Running it in high geat at WOT is going to use unnecessary gas too, due to your accelerator pump/computer dumping more fuel to compensate for the influx of air and drop in vacuum pressure. Eventually the WOT in high gear will use less gas due to less vacuum and lower RPM not being able to pull enough fuel. Either way, you're not being fuel efficient, so I don't see the point in asking. Just ride/drive like a normal human being. Who WOT's in top gear unless you're nearing top speed anyway?