Thinking of buying this car used between the years of 2000 to 2002. Does it use a timing belt or chain? Is a chain better than a belt? How often would you need to change either, and what estimate for the cost?
Any other remarks about this g20?

G20 has a Timing chain.

Timing chain is a better choice for long service life, it can last a really long time. But it is more noisy, heavier & less efficient than the alternative of timing belt.

The alternative of timing belt, which G20 does NOT have, but some other comparable cars do, is that it is cheaper to make, & maybe lighter & more efficient for power. but it does not last as long, & if u do not replace it at the right time (perhaps 80k-100k miles for Dodge 2.2L, the only one l know from experience) then breaking of the belt means fatal problems when pistons hit valves left stuck open.

In comparison when a timing chain gets old, maybe it gets a bit loose & sloppy, & valves open a little slower & later than they should, but they do not hit pistons & do not blow ur motor it keeps running but not as efficient as it could be with some service.

You have a timing chain. Actually, there r three chains. Each head has a small chain that runs the two cams & then there is one that runs around both of the cam drives & this chain even drives the water pump.

Event is chains of rebels does exist because they do not break quite as easily. However, they do stretch quite a bit & the other flip side is that they r quite a bit noisier.

The approximate cost is about $400 give or take about 50 since we r going into the front of the motor & there is always the possibility of broken parts. It is not that we expect this to happen, but sometimes it does, so u r better off with a quote bearing a safety net.

G20s r okay cars, but they r a bit underpowered. Of course the flip side to that is greater economy.
You could always rationalize it this way: it is probably capable of maintaining any speed limit in this country. If someone were looking for a high-performance vehicle, they would not be looking at one of these anyway. Infiniti is a great car, hi line of Nissan. You get a lot for ur money, & they last a long time.

Timing chain. You dont need to replace. l know this for a fact because my Dad owns an Infiniti dealership!