Yes, you're right, the Hyundai Exter AMT is not great on the highway, but frankly, given your budget, it's not the best for the city either. The AMT gearbox gets the job done, but is nowhere as smooth as more sophisticated automatics.
The Kia Sonet turbo-petrol DCT, sadly, does not fall in your budget, but it is well-equipped and upmarket, if you are willing to make the stretch. The best value options within your budget are the Renault Kiger and Nissan Magnite, which not only offer a 100hp 1.0 turbo-petrol engine but also a smooth CVT gearbox within your budget. However, they both lack the same level of quality and refinement that Hyundai and Kia offer.
Interestingly, the new Hyundai Venue is offered in 1.0 Turbo DCT HX5 guise, which is around the Rs 12 lakh on-road mark. It's more spacious and comfortable than the others and comes with a decent feature list. This is your best bet, but if you don't mind a hatchback, the Hyundai i20 is even better, as you get the choice of two petrol automatics - 1.2 CVT and 1.0 Turbo DCT - well within your budget.



