Merge them into two different sites
Motor Vehicle Maintenance and Repair:
- regular auto maintenance
- general-info and upkeep
- tag 'preventative-maintenance'
- tag 'off-road-mods'
- tag 'towing-trailers'
- tag 'winter-preparation'
- tag 'batteries'
- tag 'oil'
- tag 'tuning'
- tag 'biofuel'
- tag 'hydrogen' (they do exist, they're just very uncommon or still in the prototyping stage)
- tag 'electric'
- tag 'motorcycles'
- performance-auto maintenance
- tag 'electric-car-racing' (see the National Electric Drag Racing Association (NHDRA))
- tag 'motorcycle-racing'
- tag 'snowmobile-racing'
- tag 'rally-racing'
- tag 'NHRA' (top fuel drag racing)
- tag 'air-racing'
- tag 'kart-racing' (meaning go kart racing. I have seen one of these tracks in person, it's like mini NASCAR with little cars flying by at 90+ MPH).
- tag 'motocross'
- tag 'lawnmower-racing'
- tag 'formula-1'
- tag 'stock-racing'
- tag 'nascar'
- tag 'turbo-chargers'
- tag 'super-chargers'
- tag 'gear-ratio'
- tag 'regenerative-braking'
As you can see, motorsports covers a lot more ground than the standard daily-use Motor-Vehicles. Motorsports even has its own Hall of Fame that covers many of the different categories of motorsports.
The Motor Vehicle Maintenance and Repair users are concerned with fixing issues, maintaining their vehicles without running into issues that cost them money.
Motor Sports users are willing to spend the extra money if they can get that extra ounce of boost out of their engines. I'd see this group as doing maintenance in the same manner as the other group but in a much more specialized manner. For instance, normal car owners don't really think too much about the oil they put in their cars, performance engines OTOH often times require certain types/grades of oil because they're running at high RPMs under high stress.
The motorsports category ranges from Kart and Street Racing (which is much lower tech/less specialized) all the way to Top Fuel Drag Ragicing and Air Racing (which are both very highly specialized categories).
I'd even suggest making motorcycles its own site too because motorcycles are their own culture. If you own a bike like I do, you already know what I mean.
Electric Vehicles OTOH, will most likely just become the next generation of general purpose and racing vehicles and questions about maintaining electric vehicles will be as ubiquitous as questions about gasoline engines are today (except electric vehicles are much simpler to fix compared to internal combustion engines).
Edit: I've changed tuning to go under both proposals because it's a topic that isn't specific to motorsports. I also updated the description of both topics to better represent the spread.