Unfortunately the money from Youtube (couple grand per upload) may not be on the same level as Top Gear have been pouring into their shows. Either get investors on or find a bigger budget or scale down the entertainment side and focus a bit more editing and cinematic style reviews.
Amazon spent £4.5 million per show apparently on Grand Tour. BBC Spent around £833,000 per show. I think this includes wages of the 3 freelancers lol.
Lets say they took on Chris Harris, Rory and Matt Le Blanc on a new show. I reckon they will spend significantly more on renegotiated contracts, stunts and special effects. Around 1- 2 million per episode. As Davey said you spend the money and theres a 3+ month delay from filming to screens. Youtubers have already got first dibs on new products. Youtubers are releasing content as quickly as a day or two. Especially if they are good at speed editing.