I'm relatively new to fixing up cars but I have a mind for learning how things work. I have a 1999 Audi a6 Quattro 2.8 L and I love the car. The only thing I wish was better was the fuel economy. I know the car is old and probably outdated compared to more recent models. I really like tinkering with things and would love to start with cars. The main reason I'm posting here is to get some advice from people who know what they are talking about to get a good start.

Since my car is 14 years old I'm sure there is something I could clean in order to increase its efficiency or something cheap and simple I could add to also help, regardless of the difficulty. I also was wondering if there are any cheap projects I could do to my car for fun.

I know the biggest way to conserve fuel is to accelerate slowly and coast when approaching a stop or even putting the car in neutral when going down a very long hill. I'm not sure, however, whether or not turning off the a/c actually helps or not. Also, I heard that your supposed to fuel these cars with the highest octane gas but I have always just put in the cheapest option. Is this bad for the car and why does it matter?

 

Don't use 87 octane gas. The engine is tuned for higher octane. If you run bong-water 87, itll pull timing and reduce power and efficiency. Run 91/93. If a $6 difference in the cost of a full tank is a deal-breaker, you bought the wrong car to start with.

First off, is all due maintenance done? If needed based on time and miles driven, has the car had its timing service? Is the pressure in the tires correct and even in all four? How many miles on the spark plugs/air filter/oil? I would do any of that first if its due. Second, have the car's modules scanned for codes - ECU, ABS, chassis, etc. note and clear any codes you find. Then rescan after 100 miles of driving. Any old and treated codes will still be gone. Any that come back will need to be dealt with. Third, do a Seafoam treatment on the oil, manifold, and gas (VagSearch.com can find the procedures for you). Next, pop the PCV hose connections off the top of the valve covers (round squeeze clips). If they're all crapped up, replace that hose.

Have a go at this stuff, address anything needed, and see where that puts you. Your mileage won't be stellar in everyday driving - it's a big and heavy AWD car with only a 200hp V6 - but get it up to date on everything and it shouldn't do you too badly at all.