Driving York to Lake District then on to Glasgow

3.5 hours for each leg is more realistic. If there’s congestion, accidents, construction, or inclement weather, you can add to that. I drove from Glasgow to Keswick in 2022 and it was highway once away from the cities.

If your journeys back in 2004 took that long, there must have been an accident or road works, which can happen anywhere in the world.
Those estimated journey times are certainly realistic so long as there are no incidents. You will be able to see far using a car. The trip from York to the Lake District would involve an A road rather than a motorway across the Pennines, which will be dual carriageway for much of its way.
Up to Glasgow, once you reach the M6 from the LD it should be non-stop.
York is a very old city that wasn't built for cars. Parking can be expensive and hard to find. Is it possible to get to York by train then hire a car once you are leaving?

3 1/2 hours from Coniston to Glasgow on a direct journey is pretty slow- 3 hours is certainly realistic on a normal day.

I'm in a different part of Cumbria than Coniston, but the same distance, and am well used to the drive. 3 1/4 hours gets me to the Gourock ferry unless there are big issues on the cross Glasgow motorway- broadly an hour to passing Carlisle, then a further hour to Abington services.

The hardest part of the journey is the little road out from Coniston to Ambleside (please, please know both what reverse gear is, how to reverse and the width of your car), and congestion through Ambleside. The Coniston to Ambleside road is one of the banes of locals lives, with the number of visitors who haven't a clue how to drive on narrow roads. So many tourists get terrified at the very close quarters driving needed, especially with the buses and trucks. They will and do force you back or very close to the stone wall and pass you with literally an inch or two to spare. Seeing visitors faces when that happens is a good local spectator sport.

3 hours from York to Coniston depends a lot on your route (whether you want to go sightseeing in the Yorkshire Dales, say via Hawes) but as a straight shot over the A66 and Tebay is realistic. Again where you are likely to lose time badly is the last 15 miles or so in from Kendal, due to congestion approaching Windermere (the bad junction at Windermere station being the culprit), then between Windermere and Ambleside (notably at Waterhead) then your first attempt at the little roads on to Coniston.
You could easily lose an hour just on that last stretch on a bad day.

Thank you all for your replies. I think we're going to go for it and rent a car in York for our visit to the Lake District and transportation to Glasgow. (Yes, we are planning on train travel to York and on from Glasgow.) I will mentally plan on 4 hours for each trip excluding stops and side trips.

My husband loves to drive in England, and everywhere else so far. I'll pass the narrow roads warning on to him. As the passenger I'll just close my eyes as the wall nears. :-) Maybe there will be less traffic in the Lake District in late May since I didn't book on a bank holiday Monday.

There were roadworks in 2004, but they only accounted for about an hour of delay. Remember this was back in the days when you printed out MapQuest directions and just tried to calculate the time as best you could. As Californians used to freeways, we were probably "optimistic" about how quickly we could get from one place to another. After spending this summer mainly driving highways and mountain roads, we've seen just how long it can take to cover 50 miles. Thus my hesitancy with the time estimates since I'm equating A roads with our highways--which can drop down to 25 mph speed limits when they go through towns.

As far as I know your highways are the equivalent of our motorways, with the prefix "M" as in M6, M1 which are no stopping routes, usually 3 lanes minimum.
"A" roads can be dual or single lane carriageways and could have traffic lights and roundabouts although, some like the A66 across the Pennines are more like a two lane motorway. Many A roads in the Lake District are single lane and follow the contours.
"B" roads are minor roads and can be quite narrow.
Travelling between the major towns and cities in the UK can often be done with very little stopping these days. You always have the chance of accidents or road works to slow you down though.
Try to travel outside the peak hours of 7am-9:30am and 4pm-7pm.

I always err on the side of caution and allow plenty of time for a drive. Not only does that allow for uinexpected delays caused by an accident, it also allows for caravans and campervans as well as the tourist pootling along at 30mph admiring the scenery and completley oblivious of the increasing queue of traffic behind.

(Regulars also cover distanes a lot quicker than visitors, so (no disrespect intended) isn31c is likely to cover distances faster than you will!

From experience: when doing one's travel planning just past supper in N.America, keep in mind those driving times Google is returning are for middle of the night in Europe/UK when traffic is nearly zero. Ask me how I know 😖