Let me give you my judgement:
Chevy vs Santro
both have same capacity engines, interior,body width and length except
ground clearence for chevy is 160mm as compared to santro which is 155mm.
Drive of both cars are excellent. different opinions exists but both are quite comfortable.
Chevy has 63.8 hp vs 55 hp (santro). you cannt feel the change in drive in CNG /patrol. (both cars)
someone said that " 63.8 hp helps chevy when running on CNG ". thats true.
chevy comes with MPFI engine vs Santro as EFI.
santro as claimed by many others does good milage over CNG, i did find chevy does the same if you drive within the limits.
No one claims how much santro does in patrol that for sure. for chevy currently it is giving me almost 16.2 kms (within specified limits)
Santro : almost 80% of the car is assembled here vs Chevy 70%. the finish quality varies in santro due to high in demand but in chevy the standard remains the same for all the cars (excellent) what i have seen.
A friend of mine told me that the cars now they are trying to sell has some technical defects ( i dont know about it) but for sure i have seen the lights that are leaking durining a rainy season.
Santro price is almost same as chevy. except that chevy has standard version (fully loaded) vs santro.
Delivery time varies: i got chevy in 3 days, santro 2 months but they claim that you can get it in 10-15 days.
resale of santro is quite good as compared to chevy.
For me chevy is quite good, due to its power steering i can easily park the car anywhere. second its quite spacious from the inside though the trunk is small due to CNG cylinder. in santro they have fitted small cylinders which are fitted in the tyre compartment. this is the Plus point you can have space in the trunk.
the rear seats of santro is quite uncomfortable as they are like the seats of hiace rear seats the last one , in chevy they are rather inclined to give a smooth inclination to the back.
the engine of chevy is quite compact, thats how they easily managed to get the space.it is installed withthe latest lamaba CNG equipment same case with santro.
heavy shock absorbers & suspansion, MP3/CD with remote , indoor controlled side mirrors, central locking and power steering are the extra features in chevy. all options in the fuse box is also available like air bags and additional fog lights.
parts are all avialable in the market for both the cars.
Choice is all yours now! if you need further help you can always contact me. ( might be interested in the service manuals)
My suggestion is to make a comparision, check drive test all the cars and then buy which one you like the most!