(??) Check my Russian. My main intent was to complete the thought for a better context, so I went ahead and added my attempt as a translation.

широкий / большой интерес или волна интереса

Das ist ja der springende Punkt - das ist nämlich eine neue (d.h. erneute), große Welle des Interesses an diesem Automodell in dem Jahr. Wie kann man das am besten ausdrücken?

Новая волна интереса (?)

но extensive надо как-то перевести. The concept of NEW is in the word REFRESH, and the concept of WIDE is in the word EXTENSIVE. We need to incorporate them both.

вспыхнувший с новой силой / заново возросший интерес

👍🏼 perfect. add it!

новый всплеск интереса (?)

Yes, but you need WIDE, EXTENSIVE

Тогда сам, что считаешь более подходящим😉

👍🏼

Мальчики, мне нравится «новый всплеск интереса». Что если «широкомасштабный» добавить?

А по-моему, так это "свидетельствует о серьезном обновлении модели (автомобиля)", а не интереса.

Да, кстати👍

"Fiat-Chrysler Model Lineup to Get Extensive Refresh for 2017" - это не о Nissan, но в том же духе.
https://drivemag.com/news/fiat-chrysler-model-lineup-to-get-extensive-refresh-for-2017

A REFRESH, the way I’ve always heard it, is where a brand takes steps to spark a new wave of interest in a brand that has become stale: https://toolboxstudios.com/2018/09/15/to-refresh-or-not-to-refresh/

This is the original statement: "It's been less than a year and a half since the Leaf crossed 400,000 sales, though, and that's a testament to the model's extensive refresh for 2018. Sales have picked up in some of the Leaf's global markets—like Europe, where it was the top-selling EV for the 2018 calendar year." Here again, increased sales are due to marketing and branding measures taken to reach their global markets. At least that's how I see it.

A REFRESH, the way I’ve always heard it, is where a brand takes steps to spark a new wave of interest in a brand that has become stale:

Yes, and this is achieved taking STEPS and by changing the model in the first place.
Your translation lucks this.
возобновлённый интерес (покупателей?) - это (возможный) результат (успешного) обновления модели.

If you read the article I posted above, a refresh is a marketing campaign, not a product upgrade.

Sorry, but I am still not convinced.

A new, more contemporary logo was created
added new products
Updating your products is a great way
a minor, yet noticeable, change

Of course, all new models come with marketing, but
1. это не просто маркетинг безо всяких изменений
2. в первую очередь это действия компании (возможно, приводящие к возобновлённому интересу (покупателей)", а не сам интерес.

👍🏼