Q. Which bike is more reliable to ride in city and highway between Yamaha FZ S FI and Gixxer?

Speaking specifications, it will be difficult for fz to beat Gixxer. When it comes to mileage, I think both will be more or less the same performers. Yet, fz might have an edge because of the FI system and lighter weight.Price - You don't need an answer on that. Even if there is a difference of 5km/l in mileage (fz>gixxer), the price of gixxer is considerably less so as to balance the scale.All in all, both bikes are really good. Test ride and see which one suits you. You might want to notice the following points while test riding the bikes (my opinion in brackets);1. Posture (=)2. Suspension (fz marginally better)3, Straight line stability (both great, engine cannot overpower the chassis/suspension/rubber combo in both bikes)4. Throttle response (far better in fz)5. Pickup (gixxer ahead, far ahead after 60)6. Styling (subjective)7. Features (clock, gear indicator in gixxer)An easy way to decide is to toss a coin. If you want to go for another toss after the first one, you should know the answer ;)That is how I bought an fz v2

I took a test ride for Yamaha FZ s fi v3.0 and it's great. will be going to take Gixxer sp test ride soon. my daily traveling is 50+ km so please suggest which one should I go for ? V3.0 or SP?

Both are quite reliable. it all depends on the service and availability of spares in your area. Although personally I find gixxer more engaging to ride.