Getting Great Fuel Mileage Is Not A Trick

By Author: JD Durham
Total Articles: 41
Comment this article

Many people believe that just because they own an older vehicle that it can not get good mileage. This is definitely not true and even cars made before OnBoard Diagnostics (OBD) can get good mileage and some can even outperform OBD II cars especially when those OBD II cars are not maintained.

New cars are not the only ones that get better mileage. Even older carbureted cars can achieve decent miles per gallon. I will share information about 3 particular cars I have owned over the years to illustrate my points, that it can be done.

The first was a pre OBD 1974 Oldsmobile Toronado with a 455 C.I. engine with a 4 barrel Quadrajet carburetor. This vehicle was rated at 6 mpg highway, but always delivered 12 city and 18 on the highway.

The next was an OBD I 1984 Pontiac 6000 STE with a 2.8L v6 engine and a 2 barrel (E2SE) carburetor. This vehicle continuously achieved 24mpg on the highway at 70mph with 4 passengers.

The next was an OBD I 1991 Nissan Maxima with a 3.0L v6 fuel injected engine that achieved 27mpg on the highway with 2 passengers, and luggage while driving at 85mph.

Hopefully, I have ...
... illustrated that getting better fuel mileage doesn’t have to be a trick or a sacrifice. It means that if you keep your car in proper running order, tires properly inflated, car washed regularly, drive sanely (no jack rabbit starts), combine all your trips into a single trip, practice traffic light timing in the city when possible, and not get stuck in traffic too much you can get better mileage.

Little things can make huge differences. The tire pressure stated on the placard on your door jam or glove box is chosen by the manufacturer for both safety and ride. Too low of pressure is unsafe, but a 2psi increase will only slightly make the ride worse and most people do not even notice it! Nevertheless, a 2psi increase can give you a significant boost in fuel mileage.

Since the introduction of Electronic Spark Control (ESC) with OBD, the manufacturers have set the performance characteristics of the engine higher, but when these engines start spark knocking (detonation) the computer is programmed to retard the timing until it ceases. This is to protect the engine from damage.

What most people including professional mechanics do not know is when this detonation occurs and the computer adjusts the timing, it retards the timing in 4-degree increments. This is programmed to happen very fast! This is a huge loss of fuel economy and performance until the computer resets it to normal. This reset happens in smaller increments and very slowly. So if you are using too low of a grade of fuel, or your engine has lots of carbon build up from lack of maintenance, then you are really hurting yourself.

If your ‘Check Engine Light’ is on, most car computers are programmed with alternative performance characteristics. These can be minor modifications of ignition timing and fuel delivery, to major things like not allowing the vehicle to up shift the transmission. The driver rarely notices any changes in performance from the minor modifications, but the car is being harmed. So when that ‘check engine light’ comes on take the time to find what it is and repair it.

Recently on a UK website, http://bloodycars.co.uk there was an article where Britannia Rescue did a survey of UK motorists and found that 1 in 4 people stated their car was being driven illegally, and 1 in 7 said their car was in need of serious maintenance. Putting off performing maintenance when it is needed is a bad idea, as it costs you more now and typically the repairs will be more costly later.

If your ‘check engine light’ is on you may be able to repair it cheaply yourself, but you will need an obd2 scan tool like the 2X80S to diagnose it. If you have an OBD I car or a pre OBD car, you can get plenty of information for free on our site as well as get adapter cables.

Copyright © 2012 JD Durham

JD Durham is a World Class Technician, an Automotive Hall of Fame honoree with 45 years experience in the automotive service and repair industry and a staff writer at Straight Talk Automotive. You are encouraged to visit for more information on OBD2 Scan Tool, and OBD Bluetooth scan tool, also accept this invitation to join our FREE members only area and access great free resources.