No matter what type of car you think you are going to buy, the subject of how to propel that car deserves serious thought. There are a wide variety of engines and transmissions on the market today. As if that were not sufficiently confusing, there are several different driving systems: front-wheel drive, rear-wheel drive, four-wheel drive, and so on. You need to understand these subjects in order to make an intelligent car buying decision.

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Engines, 4-cylinder.
Four-cylinder engines are the smallest you will find, but, even so, they cover a wide range of power and economy levels. Subcompact and compact cars often come with small 4-cylinder engines designed for economy of operation, usually 2 liters or less. At the other end of the scale, some European sporty performance cars offer high performance 4-cylinder engines with power levels that rival V8's.

You may or may not have a choice of engine, depending on the type of car you wish to buy. Engine availability might prompt you to consider a different make or a larger model, however.

If you seldom drive outside the city, seldom use the expressways, and desire maximum economy, the smaller 4-cylinder engine will probably do just fine. If, on the other hand, you do a lot of high speed driving or need to carry heavy loads on a regular basis (people or cargo), the smaller 4-cylinder engines might not be enough.

The main virtue of 4-cylinder engines of all types is their fuel economy. This derives from their small displacements and lighter weight. But, they are designed to operate at relatively high revolutions, which mean they probably will not be as durable as larger engines with more cylinders. They are also easily over-stressed, which causes more problems with durability. So, if you travel at high speeds or expect to carry heavy loads, a 6-cylinder engine might be a better choice, even if you have to go up a notch in the size of the vehicle.

Although they're not offered as much as they used to be but never-the-less beware of the "stripper" car models. This is a time-honored marketing ploy to send the vast vajority of buyers looking at the fancier, pricier editions. It's neither good nor bad in itself. The problem as it relates to engine options, is that sometimes the base engine in a given line of cars will be the one that is grossly inadequate for the size of vehicle involved. So, you find some compact and mid-size cars offered with tiny 4-cylinder engines as standard equipment. You should be very careful not to buy an engine that is too small for a particular car. As a general rule of thumb, mid-sized cars should not be equipped with 4-cylinder engines and even compacts may be struggling with a 4-cylinder engine that is too small.

Engines, 6-cylinder.
Sixes tend to be much smoother and quieter than fours. Six-cylinder engines also come in a variety of sizes and ratings. There are relatively small sixes (2-2.5 liters) that give good fuel economy. At the other end of the scale, there are big bore sixes (3.5 liters and above) that are nearly as powerful as a typical V8.

A small six will give you good performance for most normal applications, as well as reasonably good economy. Such engines are good compromise choices for buyers wanting both economy of operation and respectable levels of performance. Some of the larger sixes give excellent performance, but extract a penalty on economy.

In general, 6-cylinder engines are less stressed than fours because of their larger displacements and lower engine revolutions. For this reason, sixes should be more durable than fours, even when carrying heavy loads and used for high-speed cruising. The larger sixes can even do some light trailer towing.

Engines, 8-cylinder.
Eight cylinder engines are limited to full-sized cars and some sporty/performance cars. Even so, the V8's offered today would have been considered small 20 years ago and are rated at fuel economy levels that compacts would have been hard-pressed to have beaten back then. Modern technology and government intervention has seen to that.

For a combination of smoothness, quietness and power, there is really nothing quite like a V8. That is why V8's are the most common powerplants in luxury cars, but they are also available in many less expensive and smaller models. In general, V8's do use more fuel than sixes and fours but, as noted above, even that is relative. There are many sixes--and even some fours--that do worse in fuel economy than some V8's.

For a lot of highway travel, a V8 can be a blessing. These engines are likewise exceptional for trailer towing or any kind of driving that involves lots of people or cargo on a regular basis. It is very difficult to over-stress a V8. Indeed, most of these engines are loafing at today's legal highway speeds, having been designed back when people normally drove 75-80 mph on the Interstates.

Engines, turbo-charged.
Turbo-charged engines are essentially compromises and until recent developments, suffered from the consequences. In the late-1970's, manufacturers assumed that fuel prices would continue to climb and so they sought ways to drag V8 levels of performance from 4-cylinder and 6-cylinder powerplants. The turbo-charger was one answer.

If you remember that the engine is designed to, simply put, move air, you'll understand the concept of a turbocharger easier. A turbo-charger gets more power from an engine by forcing air into the combustion chamber under high pressure. This increases the intensity of the explosion that occurs when the air/fuel mixture ignites and produces more power. So far so good. At least, that's what we all thought in the heady 70's.

Turbo-chargers do not operate all the time. A digital computer in the automobile tells the turbocharger to "kick-in," under heavy throttle load, when extra power is needed. Up until now, regulating these sophisticated computers was tricky and unpredictable. Early on, nearly all turbos were plagued by a malady known as "turbo lag" in which there was a pause, as long as several seconds between the time the throttle was punched at the flow of power kicks in. Worse, turbo lag was especially severe at low speeds where the engine was already operating at reduced revolutions. If you did a lot of stop-and-go urban driving, turbo lag could be extremely annoying.

As it turns out, the turbocharger was quite a passing fancy. It is only now with a smaller apparatus that is capable of taking in more air, are we experiencing turbo that has virtually no lag. This new generation of turbo provides immediate boost and is once again gaining acceptance, albeit slowly in automobile circles. Most of the industry, however, remains unconvinced. Many have given up on turbo. Some, though, continue to offer this assist. While it may have a checkered past, be open-minded about buying an automobile with this feature. Here are some helpful facts:

• Most turbo-chargers are fitted to 4-cylinder engines on sub-compact, compact or mid-size cars. Often, but not always, these engines are often far too small to give adequate performance in these cars without the turbo-charging. Turbo lag, in the old days only magnified the problem. But, today's torque-chargers have minimalized this problem and manufacturers have begun to offer engines in size more compatible with this feature.
  
  
• It is believed that because these systems are operating under high stress and at very high temperatures, the wear and tear is great. I'm not sure this has any statistics to prove such a point. But, to be safe, pay meticulous attention to maintenance (oil changes, etc.) on these systems. It's essential and many motorists do not want to pay that much attention to their cars.
  
  
• Turbo-chargers are not terribly economical, especially when used by someone with a heavy foot. This is surely the greatest irony of all, but the simple truth is that no matter what the E.P.A. claims, most turbo-charged engines deliver lousy fuel economy--and do it on premium fuel, in most cases, which raises fuel costs further. A turbo-charged four, for instance, is not likely to be any more economical than a standard six--and may be considerably worse.
  
  
• Turbo-chargers offer special problems when fitted to front-wheel drive cars. By their nature, front-wheel drive cars use the front wheels for both steering and propelling the car. The engineering involved is tremendously complex. In particular, one of the problems that still bedevils engineers is something known as "torque steer." When power is transmitted to the front wheels, it is not transmitted equally to both wheels. In other words, one of the front wheels will get more power (torque, in engineering language) than the other. This torque imbalance causes the car to "pull" to one side or the other, depending on which front wheel gets the most power. This is torque steer. The torque applied to the front wheels actually steers the car in one direction or another. In most front-drive cars, this is not a severe--or even a noticeable--problem. The high levels of power supplied by a turbo-charger, however, can make it very pronouced, even dangerous. We have found few turbo-charged, front-drive cars that have been able to handle this problem satisfactorily, and you can read more about them in our Road Tests section
  
  
• The only turbo-charged engines we have tested that worked really well under all driving conditions were those in which the standard engines (minus the turbo-charger) were adequate to provide reasonable levels of performance in that car. The issue really is whether the turbo-charger has been introduced to compensate for deficiency with the standard engine, or merely to augment the already reasonable power levels. This was true in may cases during the beginning of the energy crisis. Manufacturers are a little wiser now as to how to integrate the engine and turbocharger. In general, 4-cylinder turbo-charged engines work best in subcompacts, sixes and eights work best in larger cars. Rear-drive turbo-charged cars are better than front-drivers and those fitted with automatic transmissions seem to work better than those fitted with manual shift transmissions. Why this latter point is true is a question we cannot answer, but our test results bear it out.
  
  
• Significantly, many automotive experts are now begining to come out against turbo-chargers as being not worth the trouble. We used to agree wholeheartedly. The lastest generation of turbocharger, not only provides an immediate surge of power, but it typically extends this power and holds for a long time through the torques peak period, what is referred to as the torque curve. If you do buy a car with a turbo-charger, be prepared to maintain it religiously (oil changes, etc.) and seriously consider buying and extended warranty or service contract.
  
  

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There are essentially two types of transmission on the market: manual and automatic. As the names imply, one kind is shifted manually by the driver, the other shifts automatically with little driver input. In the old days, both economy and performance driving almost always required the use of a manual. This was due to the inefficieny of early automatics. Today, automatics are so efficient they are preferred by many drivers wanting sporting performance and are nearly equal (occasionally even superior) to manuals for fuel economy in most types of cars.

Manual transmissions.
The various types of manual transmissions are most easily identified by the number of gears used: 3-speed, 4-speed, 5-speed and 6-speed. Since the old 3-speed manual is virtually extinct and the 6-speed is only offered in one super-performance rig (as of this writing), the real choice is between 4-speed and 5-speed manuals. In most 4-speed units, the 4th (or top) gear is a 1:1 gear, that is, it is a direct drive ratio. The 5th gear in a 5-speed unit is an overdrive gear. The 5-speed transmissions are designed to provide quiet and economical cruising at freeway speeds.

Automatic transmissions.
Automatics come in essentially two varieties: 3-speed and 4-speed. In the 4-speed types, the 4th gear is generally an overdrive gear, again, for quietness and economy at freeway speeds. You rarely have a choice of automatics in any given car line.

Some manufacturers offer a variation of the automatic transmission. It offers the best of both types of transmissions. Each manufacturer has given it it's own name. Whether it's Tiptronic in a VW/Audi or Sportronic in a Mitsubishi the idea behind the name is basically the same. It lets you shift the gears when you prefer without--what some see as--the hastle of a manual transmission.

Transmissions, summary
The choice of a manual or an automatic really comes down to personal preference. If you like shifting gears (and many do), there are excellent manual systems available. If you want the ease of an automatic, there are likewise excellent choices on the market.

Manual transmissions are more common in smaller and sporty cars, while automatics are found more often in the larger and plusher cars. Whichever is standard, the other is often optional. A 5-speed manual will cost $75 to $200 more than the standard 4-speed, but if automatic is standard, you will get a credit of up to $800 for the manual. An automatic will run $175 to $825 extra on cars with manual 4-speed.

Four-wheel drive.
Four-wheel drive is offered in two types: off-road and high performance. The high performance four-wheel drive systems are commonly known as "all-wheel drive" in order to differentiate them from off-road four-wheel drive, but the general effect is the same: you have power going to all four wheels, rather than to just two.

• Off-road four-wheel drive is available on only a few utility vehicles and some station wagons. With this system, traction is greatly improved in sand, mud, snow, ice and off-road situations. In winter conditions, it is a great safety feature because of improved stability on slippery surfaces. Also, four-wheel-drive's ability to get through deep snow reduces the risk of being stuck in a drift and having to wait out a storm in hazardous weather and so is a popular feature in northern climates.

• High performance four-wheel drive systems (all-wheel drive) are just becoming common on some of the more expensive sporty/performance cars. As with off-road four-wheel drive, the main virtue is greatly increased traction on all surfaces.

A disadvantage to four-wheel drive systems in general includes extra weight. These systems add 100 pounds or more to a vehicle's weight, which means some increase in fuel consumption. In addition, they are mechanically complex items, which may develop problems, although long-term reliablity seems to be pretty good with those models that have been out for a while. Off-road four-wheel-drive vehicles sit higher off the ground than comparable two-wheel drive models, and might be more difficult for some people to get in and out of. High performance four-wheel drive systems are no higher than their two-wheel drive counterparts.

The extra cost of the four-wheel-drive option (it is standard on most vehicles which offer it) can run between $600 to over $4200. So, carefully consider the added cost against the use you are likely to get from it.

Front-wheel drive vs. rear-wheel drive.
Not too many years ago, all cars sold in North America had rear-wheel drive. Then, some imports introduced us to the front-wheel drive concept. The idea was picked up by a couple of domestic makes in the 1960's, but remained pretty much a novelty until the need for lighter, more fuel efficient cars became so evident in the 1970's.

The lack of a long drive shaft to the rear wheels makes front-wheel drive cars lighter. Front-wheel drive is, however, more complex because of the transaxle, the unit which takes the power to the front wheels. This has caused many headaches and repair problems.

The major high performance cars do not use front-wheel-drive. There needs to be more development done on transaxles before they can handle higher power levels. In addition, the problem of torque steer is one that limits front-drive suitability for true high performance rigs. Front-wheel-drive cars cannot brake any better that those with rear-wheel-drive, either.

Still, front-wheel-drive has some important advantages and may be the best choice for you. Traction is better in normal use. This is particularly noticeable in snow and ice. In one survey conducted during winter driving, it was discovered that most of the vehicles which had gone out of control and left the road had rear-wheel drive. Smaller cars with front-wheel drive also may have more usable room in the pasenger compartment--there is no space-devouring driveshaft tunnel to worry about.

The choice of front-drive vs. rear-drive will depend on the type of driving you do. If you live in a northern climate and do mostly sedate, family-style driving, front-wheel drive may be advantageous. If you don't have to contend with snow and prefer a high-performance driving style, rear-wheel drive will probably be your best bet.

Summary
There are many engine and transmission combinations available to the new car buyer. Consider them carefully with respect to your personal needs and driving style.