The 1973-1974 oil crisis made a lot of people start to pay attention to fuel economy for the first time. In its March 1974 edition, the magazine Car and Driver had a look at some simple DIY modifications that could be made to one of the economy cars of the time, the Ford Pinto (ack).
They came up with six fairly simple and inexpensive suggestions (see below). Not all of them are as applicable today, but some are (lots of cars with bad aerodynamics on the road), and the general spirit of the exercise is worth recapturing. Efficiency isn't enough - we need a much bigger leap forward - but it's better than nothing in the meantime, and even much cleaner cars (Plug-ins, EVs) would benefit from rolling resistance and aerodynamics improvements.
"Mod #1: Front air dam.
They started by making & installing an air dam beneath the Pinto's front bumper to divert as much air flow as possible away from the car's aerodynamically dirty underside. That single change accounted for fully one quarter of their gains.
Mod #2: Partial grill block.
Another highly turbulent air pathway is the cooling system. Most cars' grill openings are sized to keep the engine cool in absolute worst-case conditions (think Death Valley, pulling a trailer). By blocking part of the Pinto's grill, they were able to improve efficiency without adversely affecting engine temperatures in normal driving.
Mod #3: Smoother tail (rear spoiler).
The aerodynamically ideal shape at the rear of a vehicle is a gradual taper that helps minimize the size of the turbulent wake left behind. But the slope of the Pinto's rear window was too steep. By adding a six inch spoiler, they effectively changed the angle of air flow between the end of the roof and the back of the car. The result: a 7% MPG improvement.
Mod #4: Smoother nose.
While almost every new car sold today has a smoothly contoured front end, the Pinto's face left a lot to be desired. To partly address this, they made and installed convex plexiglass covers over the car's headlight buckets. That small change added 0.1 MPG.
Mod #5: Reduced parasitic loads.
Back in '74, most cars sported a belt-driven radiator fan. By removing two of the Pinto's four fan blades, it was made more efficient. Today, most vehicles have electric cooling fans that run on demand only.
Mod #6: Reduced rolling resistance.
The stock Pinto came with bias-ply tires. Switching to steel belted radials netted a 5% MPG improvement. While all new cars today come with radial tires, LRR (Low Rolling Resistance) versions are available which offer an equivalent improvement over "standard" radials."
As you can see from this chart, we haven't made that much progress. It might seem like we have since most current economy cars get in the 30 miles per gallon range at 70 mph, but compared to other technologies, a 100% improvement in 34 years is horrible, even when you consider progress in other areas (safety, comfort, etc).
Thanks to Darin at EcoModder for the tip!
::$11 worth of mods plus new tires - Car and Driver improves MPG by 25%