In our fourth installment on Materials joining our main focus is on the rising trend of adhesive technologies present in the automotive industry. As car manufacturers have new fuel consumption standards to comply with, the joining of dissimilar and lighter materials becomes crucial. Many have teamed up with research institutes to achieve these goals. Another concern is the possibility of recycling and reusing car parts after their useful life has expired. For this, there are those who are looking to nature for ideas and sustainable solutions. We also look at some interesting developments in welding and soldering to bond materials.