VVT, VTVT and iVTEC all are fundamentally one at something very similar. What they do to your motor is they modify the valve timings of delta and outlet ports regarding one another, along these lines opening or shutting the bay and outlet ports prior or later relying on various burden conditions, for example regardless of whether you need to quicken hard or you simply need to sit the motor (subsequently it gives a low measure of charge access the ignition chamber at low burden; expanding the efficiency).
Variable valve timing additionally improves the NOx (a hurtful gas) outflows from your fumes. At low and medium burden conditions it shuts the fumes port early, consequently catching some fumes gases in the ignition chamber which go about as dormant gases. These dormant gases help in letting down the temperature of the ignition chamber, consequently decreasing the NOx emanations (NOx outflows are corresponding to temperature inside burning chamber).
VTVT is called as the Variable Timing Valve Train. This is the engine technology which is used in most of the top variant cars. The VTVT technology is used in most of the cars like i20, i10 and in Hyundai verna models. In the internal combustion engine VTVT has the ability to take independent control of the intake and the exhaust valves.
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CRDI is called as the Common Rail Direct Injection. The CRDI engine works in a fashion that it makes the fuel to flow into the cylinders of the diesel engine via a single common line which is normally connected to all the fuel injectors. The main advantage of the CRDI engine is that the fuel can be supplied into the cylinders at the high pressure which leads to the better combustion. Thus both the VTVT engine and the CRDI engine has its own pros and cons. Based on your taste and budget, you can choose the best model for you. You need not give importance to the engine as based on the model that you plan to buy, you are going to get the best engine designed for that model.