The vinyl roof of the Bajaj RE can quickly become dull looking and commercial car washes make it even worse by leaving a film of chemical on the roof that makes it look dull.
There are many expensive products out there which are promoted on YouTube videos to do the job, however you really do not need to spend a lot of money.
First wash the roof at the same time you wash the Bajaj RE. A good car shampoo is all you need if the roof has ingrained dirt you can scrub it with a shoe brush (not to hard) as you wash it.
Rinse the roof very well to get rid of all the shampoo, then leather it dry.
Next spray it with a Multi-purpose Protectant, I use D’Best Multi-purpose Protectant for Leather, Wood, Acrylics, Vinyl, Rubber and Plastic, which you can buy in most hardware shops in the malls for 128 peso a bottle. One bottle lasts me about 6 months. Armor All has also been suggested, I have not used it myself but I suspect it is the same type of product.
You do not need to spray it all over just spray enough so when you wipe it with a microfibre cloth it will cover the area you are working on.
Wipe with microfibre cloth until it is even and leave to dry.
The roof of your Bajaj RE will look like new and the vinyl will have a protective coating from the weather, it also keeps the vinyl soft and prevents it from cracking.