you play just like I did when I was just starting out on SA2, only difference was I didn't know about the B+A homing attack thing for quite a while :P .
The beginning was okay, you just need to practice it and you'll be timing everything just right, same with spindashing the hills, when I first discovered it I was all over the place, but it only takes around 10-20 minutes to master it.
Just charge general spindashes for 1/2 a second, the ones on the hills don't worry about because odd are you've charged long enough just waiting to be at the next hill. when you start the truck, just charge for like 1/4 a second and let it go, the hill will do the rest.
I noticed on the rails you kept trying to do a bounce ball+homing attack which will screw you up, (this is probably why the beginning looked weird, and you missed the last rails so many times) just use the bounce ball only when it comes to any rails,or you won't ever beat me because homing attacking them is soo much slower. :P
the second half was really weird by the loop, but don't feel bad about missing the target with the ramp, it took me FOR-EVER to master that(I think I only ever started using it when I had around 1:49 because my I could never pull it off correctly)
The truck.. well, it's probably just ever so slightly slower to spindash each hill than it would be to just let it go, but the odds of not bouncing and wasting much more time is like 1/50, so anyone that wants to risk a potential 1:38 on such odds then go ahead, maybe you'll get 1:37!
Spindashing each hill probably seems hard at first because you can't see where your going(which is why I never started doing it until 1:41) but just look for signs, what I do for the first hill is hit the B button when I see the white car on the left side (from your perspective, not sonic's), pause for about 0.5 then do another spindash and I should get to the next hill, which my sign is the red car on the left side. The third and final hill is the easiest, because the sign is the ramp, I don't think i've ever failed that one, the one I screw up the most is the first.
my spindashes are done without the lightdash, because on my main file I have the light attacking thing and it's so distracting it makes me screw up more so I played CE on a new file which didn't have the lightdash, but I didn't care because CE doesn't need it anyway, just the good ol' bounceball :)
and I don't use the DC version, it's next to impossible to get a flawless run on it because the controls are weird, if you hold up you'll be going left and right all over the place as well. (Basically, it's near impossible to go in a straight line at high speeds) probably why SM only has 2:10 on CE because DC has a huge disadvantage.