If cash is high and sprinkles not so much then place a few RTTs etc for instant sprinkles. You won't have to wait, won't need so much land and the payout basic is 1 XP per $10 in-store cost ( $7.50 when sold ) compared to 1 XP per $100 for the KB Rig or Zirconia.
I used to wonder about the logic of those, but with many sprinkles I use KB Rigs to keep my cash down so I don't max out. While it doesn't mean much either way I found I hated wasting income when collecting and tried telling myself I was happy to tap for sprinkles, then decided to go burn off cash until I dropped all the way back down to $1 billion and try to keep it at about that level.
EDIT - math: RTT, $150,000 = 15,000 XP + collider = 75,000 XP + bonus ( say 900% for easy math would be 750,000 XP per truck )
KB Rig $8mil = 80,000 XP + collider = 400,000 XP + bonus ( again 900% would be 4 mil XP )
Just under $8 mil gets 53 trucks for 39.75 mil XP at that 900% bonus