The Maragaret Line Road, Izu Peninsula

We are going to hire a car in Shimoda in November and spend a day driving in the southern part of the Izu peninsula.We had planned to go to Matsuzaki maybe Dogashima and the Kawazu falls. Travelling time will be a bit tight for us and I saw one blog that said it took 2 hours and twenty minutes to drive from Shimoda to Matsuzaki on the Margaret Line scenic road whereas the more direct route is only 50 minutes (from another blog).
I have found previously that estimated travel times can be vastly exaggerated so wondered if anyone had been through the Margaret Line and knew how long it takes?

Dear TM-san,
As your understanding,there are two main lines between Shimoda and Matsuzaki.
One is route 136,they call it "Margaret line".
Another is route 15 via long tunnel under "Basara Touge(mountain pass)".
If you take the former, it usually takes one hour and half(not 2hours and 20 minutes).As you have already witten, its way is more scenic but it takes more time because it runs along the coast and inevitably some part is winding.
When you take the latter, yes, it takes 50 minutes only.
If you are nervous about driving the car abroad, taking the local bus is effective alternative.
Example itinerary is as follow.
1300 Shimoda ⇒(Via Margaret Line)⇒1432 Matsuzaki⇒loaf around Matsuzaki; Matsuzaki is very tiny but calm and old oriented town. I highly recommend a visit!)⇒1810 Mastuzaki (via Basara touge)⇒1859 Shimoda.
The local bus company is "Tokai(東海)bus" and its sales office just front of Shimoda station, you can buy "two day free pass".
Its fee is 2,790JPY.
So you can visit Kawazu waterfalls beforenoon, then visit Matsuzaki.
Kawazau waterfall is worth visiting but some part of its hiking trail has not been reformed after devastated by typhoon two years ago.
Just for your info., you can go to Kawazu waterfalls by local bus every one hour from Kawazu station of "Izu-kyuko railroad".
Bus fee from Kawazu station to Kawaza waterfalls is 580 JPY.
Have a nice trip in Izu!

Masa San
Thanks heaps for your reply. The information is just what I wanted to know.
We have driven in Japan quite a lot so it doesn't hold any fears for us.
We will have enough time to do our trip.
Thanks again!

Dear TM-san,
I feel happy to know that my comment meets your request.
But please be noted the former part of the route 136 is not so interesting. If you read some Japanese, I recommend to turn to left at HINNO (日野) around 15 minutes ride after Shimoda station, then take the route 16 instead of keeping route 136.
At first route 16 runs along the river, that bank is decorated with colonnade of cherry trees, then the scenic Pacific Ocean is waiting for you!
Just after one hour ride on route 16, you automatically get back to route 136.
The latter part of route 136, you can find it is literally "the Margaret line"
Please take care!