How to make my 1977 Cadillac Edorado have better mileage?

I know its an old car, but I love it to death.



Is there anything I can put into the car or replace to increase the mileage a bit?



Thank you.How to make my 1977 Cadillac Edorado have better mileage?____o ________O - larger (taller) tires on the drive wheels cover more ground per revolution. also a slipperier oil means less power used just to turn the engine. i have found a difference using synthetic oil.How to make my 1977 Cadillac Edorado have better mileage?
The valve clearance is a good idea. I did not think of that and if they have never been adjusted they will most certainly need it on that old of a car (not hard to do you can find instructions online, you will likely need a replacement gasket). Including adjustment of valve rocker clearance, here are some other ideas:



a) Stay away from gimmicks. The "turbo tornado," "fuel ionizers," oh and my favorite (not) the $20-$100 "chips" found on ebay etc. All total garbage. If it seems gimmicky then it is, dont waste your money.



1) Make it breathe better: For example a cheap aftermarket intake system from eBay. Preferably a Cold Air Intake [CAI] or a Short Ram Intake. CAI are typically more difficult to install than a Short Ram Intake but offer much better results because they draw cool air from outside of the engine bay as opposed to a Short Ram or stock intake system which sits next to the engine drawing hot air. Also on an old Cadillac probably has a huge engine bay so install might be easy as cake. Newer cars barely have any room in the engine bay this is what makes install of CAI tricky sometimes but your case might be an exception you might have no problem at all with all that room to route it. This option will add a couple horsepower and give your car a cool throaty sound too (slight, more when you open the throttle). Grab a filter cleaning kit from the auto parts store if you get this.



2) Make it breathe better, part 2: Exhaust components. If you car is exempt from emissions you "could" remove the catalytic converter(s) and replace them with a section of straight pipe (bad for the environment). This will usually require mechanical experience as well as a welder. Another option would be to buy an aftermarket exhaust but this is very expensive and not economical for the gains you will likely receive will be minimal (but the sound would be great!). You could also replace only the muffler (rather than the whole exhaust) with a performance high-flow muffler. The stock muffler is the second most restrictive component of the exhaust system, second to the cats (catalytic converter). Replacing the muffler and removing the cat would provide the most dramatic results of all the options in this answer, but make sure it wont fail inspection as a result (cats).



3) Tires. Other than the most obvious maintenance things like keeping your tires properly inflated and your air filter clean (which are important), there are a new product that just came around called high efficiency tires. These tires achieve less rolling resistance due to a harder rubber compound and special tread pattern. Supposedly they are pretty effective because GM is putting them on their new Chevy Cobalt "XFE" which is being sold as a high efficiency model. The tires are claimed to be one of the main contributing factors in achieving these increased MPG numbers.How to make my 1977 Cadillac Edorado have better mileage?Don't rev engine too high before changing into a higher gear, in many cases you can also miss out 3rd gear when going up the box, This should reduce fuel usage.How to make my 1977 Cadillac Edorado have better mileage?
drive mainly on the highway. I have a 95 honda civic who gets about 40 mpg on the highway at a constant 60mph but once I do city driving I start getting 20 mpg. It goes down in half! so always go for the highway or freewayHow to make my 1977 Cadillac Edorado have better mileage?I know what you mean by mileage if you want it to last longer service the car regularly and change the oil as it will put less strain on the engine as the parts will move around easier and more efficent than the next thing you have to do is check the valve clearance and adjust to the manufacturer recommendation. Check brakes,check all levels. The list could go on check tires.





If you want the car to run better on petrol you can do a few things as above i mentioned service the car regularly as it will be more fuel efficient. Now the sad part since the engine size is very big there is actually no way of making it more fuel efficient the alternative option would be is to put in a smaller engine cc.



Hope i helped and the car you have is amazing best of luck and happy driving.