Buying a car focuses on the engine, gearbox and wheelbase.
The engine can naturally inhale and supercharge. There are two main determinants: power and torque. Power represents the power of engine. The greater the power, the stronger the power, and the higher the maximum speed that the vehicle can run. Generally speaking, an engine with a power of more than 50 kilowatts is considered to have excellent performance. The method of calculating the rising power is very simple. Divide the maximum power by the displacement, and the value is the rising power. Torque represents explosive force. The greater the torque, the better the instantaneous acceleration of the vehicle and the stronger the climbing ability.
In the case of similar engine technology, power and torque are directly proportional to displacement, and the greater the displacement, the greater the maximum power and torque. Turbocharged and supercharged engines, due to the adoption of supercharging technology, burn gasoline more fully and can explode more power than naturally aspirated engines with the same displacement. For example, the maximum power of the new Regal 1.6T is 132kW, while the maximum power of the new Regal 2.4L is only 125kW. Since the small-displacement vehicles below 1.6L can get policy subsidies, many car companies are keen to launch small-displacement engines with T, which can not only enjoy preferential policies, but also satisfy the owners' pursuit of power.
Another thing to remind everyone is that the maximum power and torque must be combined with the engine speed to make sense. When driving in urban areas, the speed is generally between 2000 and 4000 rpm. If the maximum power of a car can explode at 2000-4000 rpm, then it is very suitable for driving in urban areas. The maximum power of some cars is very high, but it can only appear above 6000 rpm, so this data is basically a gimmick and doesn't make much sense. For example, a Japanese car with 1.8L engine has a maximum power of 103kW/6300rpm, which can reach 57kW, and its performance is quite good. But its maximum power must appear at 6300 rpm, which is unlikely to be achieved by driving at ordinary times, so it has no practical significance.
So is torque. Generally speaking, the maximum torque can be reached at 2000-4000 rpm, which shows that the engine technology of this car is good and explosive. This low-speed and high-torque vehicle is more suitable for driving on urban roads. If you want to reach the maximum torque value of the car above 5000 rpm, it means that "strength" is not the strength of the car.
Gearbox: The more gears, the better.
There are mainly manual gearboxes and automatic gearboxes. In order to take into account the respective advantages of manual and automatic gearboxes, some models will be equipped with manual and automatic gearboxes. Now there is a relatively new gearbox system called powershift, which is installed on some models of Volvo, Volkswagen and other brands.
A very simple way to see whether the gearbox is good or not is to look at the number of gears-whether it is manual or automatic, the more gears, the better. Good manual gears are all 6 speeds, and good automatic gears are all above 6 speeds. The transmission gears of Mercedes-Benz and BMW have reached 7-speed and 8-speed. There are many models that claim to be technologically advanced, but they are actually equipped with four-speed gearboxes. Don't be cheated. Although there is no need to shift gears, there are gears in the automatic gearbox, which are only controlled automatically by the computer. The more gears, the better the ride comfort of the vehicle, and of course the higher the price. For example, gears are like steps, two slopes with the same slope, and the one with more steps is definitely more labor-saving than the one with fewer steps. Theoretically speaking, CVT continuously variable gearbox increases the number of stages to infinity, which makes the smoothness better, so that you can hardly feel the frustration when shifting gears, but the maintainability is higher and the durability will be reduced.
Wheelbase: The longer, the more spacious.
Refers to the distance from the center of the front wheel to the center of the rear wheel. There is a certain relationship between wheelbase and vehicle length, but they are two independent concepts. Generally speaking, the longer the wheelbase, the higher the driving stability of the vehicle, the larger the interior space and the better the comfort, but the larger the turning radius of the vehicle.
Nowadays, many cars are popular to lengthen, such as Audi A4 and BMW 5 Series. The wheelbase is enlarged, which can increase the rear space and make passengers feel more comfortable, but it will affect the handling of the vehicle to a certain extent.
If you buy a car for family use and often travel with your wife, children and parents, then space is a more important consideration. The wheelbase should be as long as possible so as to ensure the comfort of the rear passengers. There should be plenty of room in the trunk to put down enough things. It is best to put the rear seats flat, which can increase considerable storage space. Refers to the distance from the center of the front wheel to the center of the rear wheel. There is a certain relationship between wheelbase and vehicle length, but they are two independent concepts. Generally speaking, the longer the wheelbase, the higher the driving stability of the vehicle, the larger the interior space and the better the comfort, but the larger the turning radius of the vehicle.
Nowadays, many cars are popular to lengthen, such as Audi A4 and BMW 5 Series. The wheelbase is enlarged, which can increase the rear space and make passengers feel more comfortable, but it will affect the handling of the vehicle to a certain extent.
If you buy a car for family use and often travel with your wife, children and parents, then space is a more important consideration. The wheelbase should be as long as possible so as to ensure the comfort of the rear passengers. There should be plenty of room in the trunk to put down enough things. It is best to put the rear seats flat, which can increase considerable storage space.
Minimum turning radius, tires, suspension and other data are also important references for car selection.
minimum turning radius
In layman's terms, it is the width required for the vehicle to turn around, which represents the ability of the vehicle to bend the ground through the narrow. When the turning radius of the car is marked as 5.5m, it means that the road width must be at least 1 1m to provide a complete turning for the car. When driving on congested urban roads, cars with small turning radius have obvious advantages, making it easier to turn or turn around.
The minimum turning radius of a car is generally about 2-2.5 times of the wheelbase.
tyre
The specification of a tire is usually expressed as: 205/60R 15, where 205 represents the tire width (mm), 60 represents the flattening rate, r represents the radial structure, and 15 represents the tire inner diameter.
The wider the tire, the greater the friction, the better the handling performance and the more comfortable it will be, but the fuel consumption will increase.
Flatness refers to the ratio of tire section width to the distance from rim to tread. The tire with high flattening rate has strong cushioning ability, but it has poor feeling on the road surface and weak lateral resistance when turning. On the other hand, it bears great pressure, is very sensitive to the road surface, has great lateral resistance when turning, and greatly enhances its maneuverability.
hang
Automobile suspension is used to transfer the force and torque between the wheel and the frame, buffer the impact transmitted to the frame or body by uneven road surface, and ensure the smoothness of automobile driving.
There are many kinds of suspension. Non-independent suspension is widely used in economy cars, but most of the intermediate cars and intermediate cars are independent suspensions. Dependent suspension has simple structure, low manufacturing cost, high strength and easy maintenance, but poor comfort and handling stability. Independent suspension has light weight and high comfort, which can improve the driving stability of the car, but it has complex structure, high cost and inconvenient maintenance. Independent suspension can also be divided into transverse arm type, longitudinal arm type, multi-link type, candle type and McPherson type. At present, most models adopt McPherson suspension, mainly because of its strong road adaptability.
With the development of automobile technology, there are also air suspension and active suspension on high-end models. The latter adjusts various parameters through the central control computer to provide the best protection for the body.
Buying an SUV focuses on the chassis, driving form and passability chassis: the non-loaded body has strong off-road ability.
There are two kinds of chassis of SUV: loaded body and non-loaded body. From this point, it can be judged whether an SUV focuses on urban or off-road models.
Non-loaded body, to put it bluntly, is that the suspension is not directly connected to the body, but connected to the frame, and a body is buckled on the frame. Its advantages are independent girder, high chassis strength and good anti-bumping performance. In addition, the four wheels are unevenly stressed, which is also borne by the frame and will not be transmitted to the body. The disadvantage is the rigid connection between the car body and the frame. When driving on the road, it is not very stable and will cause vibration.
Hard-core off-road vehicles, in order to cross-country and cope with bad roads, must have a heavy chassis, so they should use non-loaded bodies, such as Shepherd and Hummer H2. Such a car body, if you are interested in bending down to look at the bottom of the car, you will see two beams running through the front and back (but not the load-bearing car body).
The load-bearing car body is the whole car body as a whole, which is directly hung on the car body. Urban SUVs all adopt load-bearing bodies, such as CR-V and RAV4. When you open the hood, you will find that the front suspension is connected to the car body on the inside of the front fender. The advantages of this car body are: the road is very smooth, the whole car body is integrated, the natural frequency of vibration is low, and the noise is small. The integral body is safer, but the disadvantage is that the chassis strength is far less than that of the body with girder structure. When the four wheels are unevenly stressed, the car body will be deformed and the manufacturing cost will be high.
From the use point of view, the non-loaded type has almost all the disadvantages except the strong chassis, and the loaded type has almost all the advantages except that the chassis is not strong enough: it is essential to play off-road four-wheel drive.
There are two-wheel drive and four-wheel drive. A two-wheel drive SUV, you can basically think of it as a car. The off-road capability of four-wheel drive SUV is relatively better. It can distribute the engine output torque to all the front and rear wheels according to different road conditions, so as to improve the driving ability of the car. If you see the words 4X4 or AWD on a car, it means that the car has the function of four-wheel drive. Four-wheel drive can be divided into full-time four-wheel drive, part-time four-wheel drive and timely four-wheel drive.
Full-time four-wheel drive is a four-wheel drive vehicle at any time. This driving mode has good off-road and handling performance, but it can't adjust the torque distribution according to the road conditions, with high fuel consumption and poor economy.
Part-time 4wd means that drivers can choose driving mode manually, that is, they can choose two-wheel drive or four-wheel drive mode according to different road conditions. The advantage is that it can not only ensure the power and passability of vehicles, but also give consideration to fuel economy. Slightly insufficient is that the driver needs to judge the road conditions by himself and manually operate the driving mode.
Timely four-wheel drive, also known as real-time four-wheel drive, is a technology developed in recent years. It is controlled by a computer chip to switch between two-wheel drive and four-wheel drive, which can identify the driving environment by itself and control the switching between the two modes according to the change of driving environment. On roads with low adhesion, such as bumps, slopes and corners, vehicles will automatically be set to four-wheel drive mode, while on flat road conditions, such as urban roads, vehicles will automatically switch to two-wheel drive mode. Passability: The bigger the number, the better.
There are three indexes that determine the passability, namely, ground clearance, approach angle and departure angle.
The so-called ground clearance refers to the distance between the ground and the lowest point of rigid parts at the bottom of the vehicle (such as engine oil pan, oil tank or suspension arm) after the vehicle stops horizontally.
Approach angle refers to the included angle between the tangent of the front bumper and the front wheel and the ground, and departure angle refers to the included angle between the tangent of the rear bumper and the rear wheel and the ground. The greater the number of the two, the better the passability will be when going downhill or encountering humps, steps and potholes, so as to avoid the danger of being dragged to the bottom. You must have seen such a scene on the road-an SUV easily climbed the steps and drove to the sidewalk, but a car tossed and turned for a long time and could not climb up. This ability to cross hurdles is determined by ground clearance, approach angle and departure angle.
It should be noted that Japanese cars, German cars and American cars will mark the ground clearance data slightly differently. Some manufacturers mark the ground clearance under full load, while others mark the ground clearance under no load. Consumers need to look carefully when buying a car.