Hyundai Exter

As you've mentioned, the Hyundai Exter is the smoother and more refined car of the two, thanks to its four-cylinder petrol engine. 

Its transmission is also relatively more seamless, and overall, Hyundai cars have a better reputation for their sales and support network too. 

Other options you could shortlist are the Maruti Fronx or Toyota Urban Cruiser Taisor 1.2 petrol AMT. 

The CNG Hyundai Exter would be a good option for you. The CNG setup consists of dual tanks that fit under the boot floor, thus you will still have a usable boot. 

The seats are a bit firm, and the cabin is narrow, so if space and comfort are also very important, you can look at the Tata Nexon CNG. It too has a dual CNG setup below the boot floor, and the cabin is roomier than the Exter. The ride too is comfy and well composed at highway speeds.   

The Hyundai Exter is a good all-rounder and will be a nice upgrade from your existing Maruti Wagon R. However, considering you drive a lot in peak traffic, an automatic would be ideal, so you could consider stretching your budget for the automatic version of the Exter. 

However, if you want to stick closer to your 8 lakh budget, consider the Renault Kiger 1.0-litre naturally aspirated engine. The automatic version would be only slightly above the 8 lakh mark, but you will get a car that is compact enough for the city, spacious inside, and has a good ride.

In both cases, the gearbox will be an automated manual (AMT), so there will not be a significant mileage difference compared to the manual versions.     

The Tata Altroz in the Creative spec will fit in your budget and is a well-packaged premium hatchback. The dual-cylinder also allows for a decently sized boot, and it offers good power for city driving. The main advantage this Tata car has over the other cars you mentioned is a premium cabin, more features and space and comfort. It rides very well, feels plush and has good tech. The Exter has a bigger boot, and Hyundai is better than Tata when it comes to after-sales, but as a product, the Altroz is better and will suit your needs well. 

Please note, the Hyundai Exter does not come with an IVT/CVT gearbox but an AMT. 

As for your query, the Toyota Glanza AMT is the one to buy. It's got a more powerful engine and delivers superior performance in both city and highway driving conditions. As an added plus, the Glanza also feels more upmarket than the Exter. The Glanza is also fuel-efficient and is known to be cost-effective to maintain, making it an easy pick of the two models on your shortlist.