Many get stuck on the intro riff alone but rythmically, Speedway is a lesson in dancing around E w/E7 chord inversions in the appropriate timing (to keep the rhythm alive and moving). And also a lesson in when to bring it back it all back home and keep it simple stupid and sustain the chords and/or when return to the intro riff. I don't know much about the other posts w/CMaj7 and Am stuff here...maybe a different recorded version...but if you want to play the song that everyone will know and you'll rock to, here's the secret:
Lyrics - all E & 'E7 based'. Don't just strum then E7, get tasty and vamp off it dude! >> E7, E7/B, E7add6, E7/D, E7/G#, E7no3, et al (simple forms with 1 note changes to the previous chord works best) - funked up, acid-tinged, campfire strum along... And then throw in a timely: E7sus4no5/D >> E7no3/D (simple forms) - you'll know when (...ain't got nothin to say... '___' '__').
I'm no chord afficianado (had to cheat and look at examples to explain examples to you), so here's a more basic explaination of E7 chords needed. Try playing a E7 chord and moving your pinky/ring/middle/index or finger around (up or down or off until it sounds right), and then remember that 'inversion' position and use them. Also try playing 2-3 notes instead of the whole chord, or moving the bass notes or top end notes around - both on a held E7 chord guts.
See example inversions here - plug 'em in:http://www.chorderator.com/
Chorus: G/D/Asus (A) Keep it simple, and sustain he G & D, but play with emphasis 1x when played. Would get a little fancier on the A - try going up positions on the A to work up (slide up fret below to the chord to for affect) all the way to the octave and give it brilliance and sustain there with a slides off before back to the E7 workhorse.
I might be able to share a few ideas of chords at a later date if some one is interested. Let me know.