Of the different options mentioned by the moderator, buying the car after one arrives in Nepal would be my best advice. Only last month, the press (February 27, 2017) reported here that more than 3000 brand new cars from Maruti to Hyundai all imported from India were gathering dust at the Birgunj Customs Yard on Nepal border. Therefore, I cannot guarantee success, but who knows, you may well be able to take advantage of the oversupply of cars already in the country (read with badly sagging sales), to get a good price particularly for yourself - and if you are an °µÍø½ûÇø with a flair for bargaining, this is your golden opportunity to have a go at it, in the knowledge that the odds are your favor in the current situation, or at least as long as the car market stays distorted, with falling sales, etc. the way it is going now.
If you buy a new car in Nepal, however you should do so in the knowledge that you will have to pay the car dealer nepalese import duties running as high as a whopping 240% on that new vehicle. Therefore, if you might well consider another option, which is buying a good second car again after your arrival here, thus sidestepping those taxes, and here I am thinking of a 1 or 2 year old low mileage vehicle of your choice. (Take a good mechanic with you, to help you make the right choice) This will be a lot cheaper for you.
If you need financing, you should know that as a direct result of this credit squeeze imposed on the lending institutions, margin money requirements on car purchases have jumped from 10 to 20% last year to 50% down, presently. The other advantage of a 1 - 2 year old car is that it is definitely finance able whereas much older cars are not.
Personally, I would never consider importing a car from my home country. Apart from import duties and all the rest of the hassle, administrative headaches, you name it, not to mention those high import duties, remember that Nepal is a land locked country. So depending on which country you are from, the car from your home country may well have to be shipped, first by sea to Calcutta Port which is not next door! (allow 1-2 months) And after your car is cleared there by Indian customs, the car has first to be transported from Calcutta to Birgunj in Nepal by rail, and then from Birgung to Kathmandu by land/truck. Customs time again in Kathmandu!