The Jurassic Coast stretches 95 miles along Dorset and East Devon, and was made England's first natural World Heritage Site in 2001. There's no single coast road. Instead, drivers follow the A35 inland between Poole, Dorchester and Bridport, branching south to the coast at places like Lulworth, Weymouth, West Bay and Lyme Regis. Most of the fuel cost comes from those branches, not the main road.
The A35 and the side roads
The A35 itself is a mix of dual and single carriageway with reasonable economy. The roads down to the coast are another matter: narrow, often steep, and busy in summer with queues for car parks. Durdle Door, Lulworth Cove and the beaches around Charmouth all involve slow, steep approaches. Climbing back up after a day on the beach, with a full car, is where economy suffers most.
The ferry shortcut
At the eastern end, the chain ferry between Sandbanks and Studland crosses the mouth of Poole Harbour in a few minutes. Driving round the harbour instead means a much longer road journey through Poole and Wareham. The ferry charges a fare, and in summer there can be queues, but for trips between Bournemouth and the Purbeck end of the coast it often saves both fuel and time.
A worked cost
For a 95-mile drive along the coast in a car averaging 45 mpg, at an illustrative 140p a litre, fuel costs about £13.40. With summer traffic and the extra effort of the cove descents, allowing a 15% economy penalty, it's about £15.40. If you're staying for a week and making a trip each day, the side trips can easily cost more than the drive along the coast itself.
Refuelling and charging
Fill up in Bournemouth and Poole, around Wareham and Wool, in Dorchester and Weymouth, or in Bridport near the western end. Small coastal villages rarely have forecourts. For electric cars, the larger towns have the most charging; many coastal car parks don't. Avoid the temptation to search for fuel down a narrow coastal lane when you're running low; head back to the A35 instead.
When to go
The coast is busiest in the school summer holidays and on bank holiday weekends, when car parks at Durdle Door, Lulworth and West Bay fill by mid-morning. Spring and early autumn are quieter and often bring settled weather. Fossil hunters favour winter and early spring, when storms expose new material on the beaches around Charmouth and Lyme Regis, though the cliffs are also at their least stable then.
Safety on the cliffs and beaches
The Jurassic Coast exists because these cliffs are constantly eroding. Rockfalls and landslips happen without warning, so keep away from the base and the edge of cliffs, and follow any closure signs. On the beaches, check tide times before walking round headlands, which can cut you off. Those risks matter more than any fuel calculation.
Car-free options
The coastal bus services and the South West Coast Path make it possible to see parts of the coast without the car. Walking a stretch of the path and returning by bus avoids the steep car-park approaches altogether, and some of the best views are only reachable on foot.
A second example: a week of day trips
Staying in Dorchester for a week and driving out to a different part of the coast each day, at around 30 miles a round trip, adds up to about 210 miles. In a car averaging 45 mpg at an illustrative 140p a litre, that's about £30 of fuel. Choosing a base close to the beaches you most want to visit, and walking or taking the bus on some days, can cut that noticeably.