Despite the upcoming Tesla Model 3 being the company's cheapest car to date, early adopters are willing to splash the cash, bumping the price up by as much as 66% to get more performance and features.

Due to go on sale before the end of 2017, the Model 3 is expected to cost from $35,000 (£28,000). But Tesla superfans are ignoring the car's biggest feature – costing half the price of the next model up, the Model S – and instead are prepared to add between $10,000 and $20,000 of optional extras and performance enhancements to their order.

Analyst Ben Sullins used data from almost 8,000 Model 3 reservation holders to calculate how much will actually be spent on each car. Published by Electrek, the data suggests most reservations holders are prepared to pay between $45,000 and $55,000 for their Model 3, despite the larger, faster and better-equipped Model S starting at $70,000, or even less on the second-hand market.

Although most specifications for the Model 3 remain unknown – including what optional upgrades will be available – Sullins claims standard versions of the car will be very rare among the first to leave the production line. Most are looking for a larger battery to extend range beyond the 215 miles Tesla boss Elon Musk says the entry-level car will be capable of.

Tesla's autonomous driving system Autopilot is also expected to bump the Model 3's price up significantly. Musk has said the car will offer the same system as seen on the Model S and Model X, but as with other options the price here is unknown for now.

Musk has previously said he expected the average selling price of the Model 3 to be around $42,000. Prices for the UK have not yet been announced, but currency fluctuations in the wake of the Brexit vote two months after the Model 3 was revealed are expected to see early estimates of £30,000 revised upwards.

To remind customers that the Model 3 is not the company's new flagship, Tesla said in a blog post on 6 April: "Model 3 is smaller, simpler, and will come with far fewer options than Model S... [it] offers a good range of at least 215 miles for our starting model."

Since it was revealed in April 2016 more than 400,000 people have placed pre-orders for the Model 3. If Tesla can ramp up its production speed to deliver cars on time, the Model 3 and its BMW 3-Series-rivaling price and size could one day be looked back upon as a pivotal moment in mass-market cars switching from internal combustion to electric power.