Electrical Engineer Ron Gremban has tinkered a bit with his Toyota Prius, and using a "plug-in" battery stack, has radically increased his fuel efficiency to 80 MPG. Others using similar technology have achieved 250 MPG. Right now the battery stacks are not deemed cost effective (requiring a $3,000 USD investment), nor are they commercially available, but that time should come soon - especially with gas prices pushing $2.75 / gallon stateside.
Tipping point
