With a properly tuned and maintained engine, used car fuel economy and emissions need not be poor.
But don't old cars waste limited petroleum and pollute our air and water? Yes and no. Nobody should operate a gas-guzzling, oil-dripping, smoke-billowing junker except to get it to a mechanic or junkyard. But, when run hot over country distances and at road speed, a properly maintained-and-tuned older car is cleaner than a poorly maintained new model and used car fuel economy is acceptable.
Only when large numbers of city cars stop and go without driving far enough to warm up, then idle at stoplights or inch along in urban gridlock, do pollutants build up (and when EGR valves open, computers earn their keep, and catalytic converters light).
Across this huge nation, only Los Angeles County in California continues to have intractable air quality problems. Still, the EPA wants to impose the (super-strict, yet ineffective) California standard nationwide—when both nuisance value and cost far exceeds any environmental benefit.
As for water pollution, the lead is out of gasoline and the rest is up to us. Years ago I drained antifreeze onto the ground while old oil sat around in leaky milk jugs. I use the new Sierra Brand of nontoxic/biodegradable antifreeze containing propylene glycol and will try to have that recycled/rejuvenated annually rather than changing it each year. Our town dump accepts old oil for recycling. If they didn't I'd pay a gas station to dispose of it, which is mandated by law in 21 states and should be everywhere, as a single 4-quart oil change can pollute a million gallons of water.
Fuel efficiency is largely a function of vehicle weight, and weight a function of size and relative content of heavy steel vs. light-weight aluminum or composite. The current economy champ is the Japanese-import Geo Metro, a tiny, thin-steel unibody model that gets 55+mpg and weighs only 1,621 lb. But have you seen one after a wreck? They fold up like tin cans. I wouldn't drive one as long as there are I8-wheelers on the road.
You can do very well by being fuelflow conscious; keep speed low and the gear as high as you can so long as the engine doesn't labor. Pretend there's a raw egg between your foot and the accelerator pedal; a gentle pressure won't break it, but let go or jerk hard and Krakk!
Here are four things you can do to reduce your older vehicle's pollution potential by 70% or more without harming performance.
1. Fuel can gush out to soften tarmac and evaporate into the air when air is trapped in an old-style unvented filler pipe. So, listen as you fill. When capacity is about reached, the sound will change to a gurgle and then to a higher pitched roar as fuel rushes up the pipe. At the first change in tone, release the lever.
2. To burn crankcase fumes, install a PCV (positive crankcase ventilation) system. At any auto dealership, buy a PCV valve and grommet and a PVC aircleaner filter and grommet for a modern auto of your engine's size. Drill holes to install the valve in a valve cover, and the filter in the aircleaner and connect with fuel-proof rubber hose. Look at any new car for an example.
3. Reduce exhaust emissions by installing a catalytic converter (a pair or a dual-in/dual-out unit for old-time real dual exhausts). Have a genuine exhaust system expert (not a muffler shop) locate and install it in your exhaust system so it will heat up enough to fire off but be shielded so as not to burn the vehicle or ignite leaf piles in the gutter. The best deal I know comes from Don's Hot Rod Shop. Don sells universal free-flow converters for 2"' to 2 1/2" -diameter pipes for about $80. Converters for a muscle car's 3" pipes cost more.
4. Treat your car or truck as you should any tool and take care of it. Especially, keep it in tune—so that the correct gas and air charge gets a hot spark to detonate inside the engine at the right time. Have it done for $50 if you must, better to get a book, wrench set, feeler gauges, timing light, and tachometer and learn how to keep your car in tune in your own garage. Go to Instant-Lube or buy ramps, grease gun and a drain-pan and change engine oil and filter and lubricate from one end to another each 2,500 miles or two months. Inspect, clean and gap spark plugs and points, change air and fuel filters every three months. Change all lubricants, points, plugs and distributor cap and adjust valves each six months. Perform all other routine maintenance twice as often as repair manuals direct (at half the recommended mileage). Replace all belts, ignition wires, fuel pump and coil every 20,000 miles or two years, all hoses and water pump every 40,000 miles or five years and replace battery six months short of its recommended service life.
After investing less than $250 for tools and then an hour's work and $50 every month after that, you will have a good-starting, reliable, clean-burning vehicle and preempt 99% of problems before they happen.