Digital Traveler: These car-rental sites lack muscle

— -- Shopping for a rental car online is often an afterthought for many travelers, a casual mouse-click to be lumped in with the more pressing quests of finding cheap airfares and hotel rates.

That most travel shopping sites, such as Travelocity.com and Carrentals.com, usually have the same range of rates from major rental companies reinforces the notion that the process isn't worth fretting over.

Travelers determined to shave a few bucks turn to Priceline or Hotwire. But with these "opaque" sites, you can't choose your rental company and must prepay. Rental companies and other travel agencies normally let you book without advance payment and cancel anytime.

Coupons and discount codes float around the Internet, but who has time to hunt them down?

A couple of emerging sites — Autoslash.com and Vroomvroomvroom.com— hope to stir up the staid business with promises of low prices and a more engaging shopping experience.

After a trial run for a four-day rental at Los Angeles International airport, we were particularly impressed with Autoslash, although it failed to point us to the cheapest option.

After you reserve a car, the 15-month-old site continues to search for coupons or rate changes, and alters the reservation to reflect a lower price.

In our LAX trial, the cheapest rate for a midsize car that Autoslash found was $264.12. Two hours after the reservation, it sent an e-mail alerting us to a discount and automatically lowered our price to $251.49.

But Autoslash showed only seven companies at LAX and didn't disclose cheaper options available at the airport. Expedia compared 13 companies and found cheaper offers of $122.80 and $152.73, albeit from the more obscure Midway Car Rental and U-Save.

Vroomvroomvroom.com was less impressive, though it offered easy search functions and rendered 12 rate results. Its prices weren't cheaper than other sites, and it offered no compelling reason for customers to switch.

Here's a closer look:

Autoslash.com

•Pros: Looks for coupons and rate changes even after reservation is made.

•Cons: Shows fewer vendors. Failed to show cheaper rates found at other sites. Hotwire was also cheaper, at $193.90.

•Takeaway: Offers new shopping feature, but cheaper rates may be found elsewhere.

Vroomvroomvroom.com

•Pros: Clean, simple site. Found a cheap deal not offered by other sites (a van for $204.72). Says it offers price difference and $10 if you find a cheaper rate elsewhere.

Cons: Prices are generally same as other sites.

Takeaway: A me-too product, though you may occasionally find a deal.

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