Here is a set I got from Amazon for an older car, they work quite well in blocking direct sunlight and UV rays but there are several other options to pick from.

Amazon.com: kinder Fluff Car Window Shade (4Pack)-The Only Certified Car Window Sun Shade for Baby Proven to Block 99.95% UVR - Mom's Choice Gold Award Winning -Car Window Shade for Baby- Car Seat Sun Protection : Automotive
Buy kinder Fluff Car Window Shade (4Pack)-The Only Certified Car Window Sun Shade for Baby Proven to Block 99.95% UVR - Mom's Choice Gold Award Winning -Car Window Shade for Baby- Car Seat Sun Protection: Side Window Sunshades - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com