1. Do you save more gas when you have your car at neutral gear instead of D at red light? Yes, but not as much as turning it off - many modern cars will do this for you, restarting when the brake is released. 2. Do you save more gas if you use vent instead of air conditioning? How about heater? "Vent", or open window? Using the fresh air vents should be negligible either way, windows are better up to approximately 80-100kph (50-60mph), depending on vehicle - the increased wind resistance will generally make A/C more economical after that. 3. Is using gear break (shifting down) better than using too much breaks when slowing down/stopping? For example, is switching to D -> D3 -> D2, etc to slow down better than just using breaks? IMO, using anticipation and coasting to a stop, using the brakes if required, is the better policy, overall. Modern vehicles may shut off the fuel on coasting/over-run but the attendant engine and transmission wear, IMO, is greater than the wear to the brake pads and rotors, certainly of greater expense. 4. Does turning on heated seats use up gas? Bad fuel economy? They require electrical energy which is produced by the engine, I would expect this to be barely noticable, though. 5. Is it a good idea to "warm up" the car before you start driving? For example, waiting about 30 seconds to 1 minute before you start driving after ignition. Generally, a BAD idea - it is when the engine is using the highest fuel/air mixture with the attendant high dilution of the lubricating film on the bore - increased wear. It is also using the fuel without moving the vehicle. However, in extreme conditions, a short idle period may be a good idea to ensure oil flow. In either case, IMO, little more time than required to put on your seatbelt after starting the vehicle. 6. Is it better to change your engine oil more than you are required to? For example, changing your engine oil every 3000 miles instead of 5000 miles like you are required to. Depends on the operating conditions, manufacturers recommendations, oil type used, whether the filter is also changed, etc. If the vehicle is used for short runs, in traffic with extended idle periods, in the low gears, in winter when it doesn't warm up, then changing the oil more frequently is a good idea as it would suffer from oil dilution from the fuel and condensation of water in the oil. If the vehicle is used in warm conditions, used mostly for long trips, is primarily used in the high ears, is rarely used cold, then the oil change period can be extended. 7. Is it a good idea to put premium fuel once in a while to "clean" your engine even though your car requires regular unleaded? Using a higher than specified fuel grade is generally just a waste of money - however, some people have actually experienced better fuel economy and/or better running from a higher grade fuel - esp' if the engine has an engine management system that will advance the timing to benefit from the higher octane. It's your call if the additional fuel cost will pay off. 8. In the United States, are ARCO fuel really bad compared to Shell, 76, Exxon, etc? Don't know, not in the US, however, most companies get their base fuel from a common distribution network and add their own additive packages. 9. How important is it to get those "recommended" 10,000, 30,000, 50,000, and 100,000 mile services for $100-200? It is a very good idea to use the manufacturers recommendations - they should know what is required - esp' when it comes to sell the vehicle as it looks like the vehicle has been well looked after. Esp' in Europe, people like to see the stamps in the service book.