Engine Technology - sajid
I have been interested in reading about the efficency of petrol engines,diesel engines, and for every gallon of fuel 3/4 of it is wasted, it got me thinking whether modern engines are more efficent.

On the other hand anyone heard about stirling engines, they are external combustion engines, and are reputed to be 80% efficent,wonder if any manufacturer is thinking about introducing them.

Another kind of engine is the orbital engine, a 3 stroke machine,last time i heard was ford have been experimenting, we have cars made by various manufacturers promoting safety, space efficency, but not about fuel efficent, any comments to why manufacturers not introducing new types of engines.
Engine Technology - Malcolm_L
Check out this website - www.howstuffworks.com/stirling-engine.htm - very informative.

Stirling engine is a closed cycle engine which uses an external heat source to expand gas which is used to power either a piston or a rotary cylinder. It's very efficient and quiet and was used by Russian submarines.

Lot of research into Stirling engines at the moment, mainly because of the potential efficiency.

Fuel efficiency has increased significantly over the years, I've been driving for 25 years and my first car (1600cc) was as thirsty as the Mondeo 2.5 V6 I used to run.
All things considered - if I drove the Mondy the way I used to drive the Renault it would be a damn sight more juicy, goes to show it aint the car - it's the driver.