Yes, gas and gadchets (computers, cameras, phones, etc) are cheaper. There are some fake imitations around also.

Respect to the car issue, even if its convenient to have one, you can probably go everywere by bus or bike. Islands have a reduced sense of distances and are a small world. Tenerife Island has around 70Km from one point to the other extreme. Other islands are smaller. Some people love it, other go into claustrophobic mode after a while. People often escape by ferry to other islands or fly to the continent some days to reset.