Vehicles are available in many different configurations to suit a customer's budget and needs. For example, optional airbags might not be a priority to a car buyer who rarely carries passengers. If you're interested in a certain car, you should read up on its crash test data. Side curtain airbag quantity alone doesn't tell the whole story -- some vehicles will use one airbag to cover all windows whereas others will use a separate airbag for each window.
We're able to see how side curtain airbags affect safety scores by studying Insurance Institute for Highway Safety (IIHS) crash tests conducted on cars with and without side curtain airbags. The IIHS notes that side impact crash test ratings can be compared across vehicle type and weight categories, but for simplicity's sake, we'll focus on comparisons of the same vehicle. The rating system follows this scale: Good, Acceptable, Marginal and Poor.
First, we'll look at a 2002-2006 Toyota Camry without side curtain airbags and a 2004-2006 Camry with side curtains. (The discrepancy in model year range reflects the addition of the side curtain airbags for 2004; though it is described on the IIHS site as "side structural changes," Toyota reported that these changes alone would not affect test results without the airbags.)
The Camry without side curtain airbags was given an overall rating of Poor. For head protection, its driver safety rating was Poor and the rear passenger rating was Marginal [source: IIHS]. But the Camry with side curtains was rated Good overall, with Good ratings for both driver and rear passenger head protection [source: IIHS].
For car buyers who've got soccer practice duty, IIHS also tested the 2006-2007 Dodge Grand Caravan. Again, side curtain airbags were responsible for an increase in driver and passenger safety. The minivan without side curtains rated Poor overall, Poor for driver head protection, and Marginal for rear passenger head protection [source: IIHS]. However, the minivan with side curtains earned an Acceptable overall rating, with Good ratings for driver and rear passenger head protection [source: IIHS].
On the next page, you'll find lots more information about airbags and other automotive safety features.