I've never been able to do one or the other to any significant and/or consistent degree to know if makes a difference. I'd be willing to bet that most folks can't either, only because isolating all the driving variables to conduct a specific experiment is difficult to do. However accelerating slowly seems to be preferred.
When given the chance I'll accellerate at a modest rate. When I'm at speed I'll tend to use short, agressive bursts if I need a 10
MPH bump. Cruisng at steady speeds does more for me than anything.
Enjoy your car!
