No problemo.
Instrumentation is the best return on investment you can make. If you drive a regular route (eg. commute), you now have a way to start measuring your performance and challenging yourself to improve. With high frequency/resolution -- beats the heck out of monitoring tank by tank.
Study the
100+ Hypermiling Tips, make sure your tires are pumped up, and have fun with it.
The SG will also let you more accurately monitor things like your coolant temperature, so if you choose to make a simple grille block (you can do that yourself), you can ensure you've not blocked off too much.