I have heard that cars with manual transmissions are more durable and economical then those with automatic transmissions. Is this so?
No, Some years ago manual transmissions were more durable and made the vehicle more fuel efficient than automatics, but now you can kiss that rule goodbye. This turn of events comes from two significant changes; lighter weight materials, and automatic transmissions, which have become more efficient in transferring power from the engine over the years. While the automatics have been steadily marching forward, most manual transmissions have just become lighter and smaller.
This brings us to a very important point. When you buy your next car don’t buy a manual transmission unless you enjoy the sport of shifting. Simply stated, if you’re a person who hates to shift but purchases stick shift only because you think it’s more durable, buy an automatic. Given proper care and usage the automatic will usually deliver nearly equal gas mileage and life.
Whether there is a penalty in fuel economy between automatic and manual transmissions depends solely on the skill of the driver. Usually automatics doing slightly better for Real World drivers. That's due to the fact that proper manual transmission driving skills are not usually taught these days.