Ken Elmore, dean of students at Boston University, poses with Zipcar on campus. (Zipcar)

As marketing campaigns go, we're not sure why Zipcar is halving its rental prices on Election Day, but hey -- if you can get around town faster and cheaper than the T, we'll take it.

Zipcar customers can rent hybrids, the company's cheapest rate, for $4 per hour anytime Tuesday from 5 a.m. through 9 p.m., right about when the polls close. It's worth noting that a round-trip T fare, minus all the waiting, now costs $5. When you factor in the superpower of legally parking in Boston's wide-open commercial zones (Zipcars all have commercial plates), the day gets even sweeter. Of course, if the T's cash tiller is broken -- not uncommon on most Green Line trains -- you ride for free and beat Zipcar hands down.

All of Zipcar's models are available at half price during the same times, including its big Econoline vans (now $7.88) and luxury cars like the Audi A3 ($6.75). Full-day rentals are not included. As another downside, Zipcar customers must first pay up to $60 per year to use the service, although many discounts are available that knock the price down to as little as $15.

However, we should say this: If you absolutely need a car to get to a polling center, then your town probably doesn't offer Zipcar in the first place.