How well can Prius PHV demonstrator accelerate without activating ICE?

A pointed question (or three) -

How much truth have you found with the statement below about the Prius PHV demonstrator?

Can it accelerate 6 MPH/sec, without ICE (well within EV range)? If not, what rate can it accelerate w/o ICE?

'The powerful lithium-ion battery packs ensure strong, seamless acceleration up to approximately 60 mph on electric-only power.'

taken from http://www.toyota.com/upcoming-vehicles/prius-plug-in/

I ask for a few reasons. When I drove the demo PHV at GreenDriveExpo, it unfortunately had only ~ 1.5 miles EV range left. We were hardly moving and the ICE came on for a bit.

Still had some range left. Came to a stop and accelerated modestly, and the ICE came on again, then went back off as we drove into the parking area.

Secondly, I find the worst fuel economy in my 2009 with short hops between nearby stores, and that's without cabin heat. I would hate to see the PHV firing a cold ICE here and there for a boost.

With EV range, can I drIve well with flow of traffic and avoid activating the gas engine?

TIA